devicetools

This modules implements the fundamental features for structuring HydPy projects.

Module devicetools provides two Device subclasses, Node and Element. In this documentation, “node” stands for an object of class Node, “element” for an object of class Element, and “device” for either of them (you cannot initialise objects of class Device directly). On the other hand, “nodes”, for example, does not necessarily mean an object of class Nodes, but any other group of Node objects as well.

Each element handles a single Model object and represents, for example, a subbasin or a channel segment. The purpose of a node is to connect different elements, and, for example, to pass the discharge calculated for a subbasin outlet (from a first element) to the top of a channel segment (to second element). Class Node and Element come with specialised container classes (Nodes and Elements). The names of individual nodes and elements serve as identity values, which is why duplicate names are not permitted.

Note that module devicetools implements a registry mechanism both for nodes and elements, preventing from instantiating an object with an already assigned name. This mechanism allows to address the same node or element in different network files (see module selectiontools).

Let us take class Node as an example. One can call its constructor with the same name multiple times, but it returns already existing nodes when available:

>>> from hydpy import Node
>>> node1 = Node("test1")
>>> node2a = Node("test2")
>>> node2b = Node("test2")
>>> node1 is node2a
False
>>> node2a is node2b
True

To get information on all currently registered nodes, call method extract_new():

>>> Node.extract_new()
Nodes("test1", "test2")

Method extract_new() returns only those nodes prepared or recovered after its last invocation:

>>> node1 = Node("test1")
>>> node3a = Node("test3")

>>> Node.extract_new()
Nodes("test1", "test3")

For a complete list of all available nodes, use method query_all():

>>> Node.query_all()
Nodes("test1", "test2", "test3")

When working interactively in the Python interpreter, it might be useful to clear the registry completely, sometimes. Do this with care, because defining nodes with already assigned names might result in surprises due to using their names for identification:

>>> nodes = Node.query_all()
>>> Node.clear_all()
>>> Node.query_all()
Nodes()
>>> node3b = Node("test3")
>>> node3b in nodes
True
>>> nodes.test3.name == node3b.name
True
>>> nodes.test3 is node3b
False

Module devicetools implements the following members:

• DeviceType Type variable.

• DevicesTypeBound Type variable.

• DevicesTypeUnbound Type variable.

• Keywords Set of keyword arguments used to describe and search for Element and Node objects.

• clear_registries_temporarily() Context manager for clearing the current Node, Element, and FusedVariable registries .

• FusedVariable Combines InputSequence and OutputSequence subclasses of different models, dealing with the same property, into a single variable.

• Devices Base class for class Elements and class Nodes.

• Nodes A container class for handling Node objects.

• Elements A container for handling Element objects.

• Device Base class for class Element and class Node.

• Node Handles the data flow between Element objects.

• Element Handles a Model object and connects it to other models via Node objects.

---

class hydpy.core.devicetools.Keywords(*names: str)

Bases: set

Set of keyword arguments used to describe and search for Element and Node objects.

device: Optional[Union[hydpy.core.devicetools.Node, hydpy.core.devicetools.Element]]

startswith(name: str) → List[str]

Return a list of all keywords, starting with the given string.

>>> from hydpy.core.devicetools import Keywords
>>> keywords = Keywords("first_keyword", "second_keyword",
...                     "keyword_3", "keyword_4",
...                     "keyboard")
>>> keywords.startswith("keyword")
['keyword_3', 'keyword_4']

endswith(name: str) → List[str]

Return a list of all keywords ending with the given string.

>>> from hydpy.core.devicetools import Keywords
>>> keywords = Keywords("first_keyword", "second_keyword",
...                     "keyword_3", "keyword_4",
...                     "keyboard")
>>> keywords.endswith("keyword")
['first_keyword', 'second_keyword']

contains(name: str) → List[str]

Return a list of all keywords containing the given string.

>>> from hydpy.core.devicetools import Keywords
>>> keywords = Keywords("first_keyword", "second_keyword",
...                     "keyword_3", "keyword_4",
...                     "keyboard")
>>> keywords.contains("keyword")
['first_keyword', 'keyword_3', 'keyword_4', 'second_keyword']

update(*names: Any) → None

Before updating, the given names are checked to be valid variable identifiers.

>>> from hydpy.core.devicetools import Keywords
>>> keywords = Keywords("first_keyword", "second_keyword",
...                     "keyword_3", "keyword_4",
...                     "keyboard")
>>> keywords.update("test_1", "test 2")   
Traceback (most recent call last):
...
ValueError: While trying to add the keyword `test 2` to device ?, the following error occurred: The given name string `test 2` does not define a valid variable identifier.  ...

Note that even the first string (test1) is not added due to the second one (test 2) being invalid.

>>> keywords
Keywords("first_keyword", "keyboard", "keyword_3", "keyword_4",
         "second_keyword")

After correcting the second string, everything works fine:

>>> keywords.update("test_1", "test_2")
>>> keywords
Keywords("first_keyword", "keyboard", "keyword_3", "keyword_4",
         "second_keyword", "test_1", "test_2")

add(name: Any) → None

Before adding a new name, it is checked to be valid variable identifiers.

>>> from hydpy.core.devicetools import Keywords
>>> keywords = Keywords("first_keyword", "second_keyword",
...                     "keyword_3", "keyword_4",
...                     "keyboard")
>>> keywords.add("1_test")   
Traceback (most recent call last):
...
ValueError: While trying to add the keyword `1_test` to device ?, the following error occurred: The given name string `1_test` does not define a valid variable identifier.  ...

>>> keywords
Keywords("first_keyword", "keyboard", "keyword_3", "keyword_4",
         "second_keyword")

After correcting the string, everything works fine:

>>> keywords.add("one_test")
>>> keywords
Keywords("first_keyword", "keyboard", "keyword_3", "keyword_4",
         "one_test", "second_keyword")

class hydpy.core.devicetools.FusedVariable(name: str, *sequences: Union[Type[InputSequence], Type[OutputSequence]])

Bases: object

Combines InputSequence and OutputSequence subclasses of different models, dealing with the same property, into a single variable.

Class FusedVariable is one possible type of the property variable of class Node. We need it in some HydPy projects where the involved models do not only pass runoff to each other but share other types of data as well. Each project-specific FusedVariable object serves as a “meta-type”, indicating which input and output sequences of the different models correlate and are thus connectable with each other.

Using class FusedVariable is easiest to explain by a concrete example. Assume, we use conv_v001 to interpolate the air temperature for a specific location. We use this temperature as input to the evap_v001 model, which requires this and other meteorological data to calculate potential evapotranspiration. Further, we pass the calculated potential evapotranspiration as input to lland_v2 for calculating the actual evapotranspiration. Hence, we need to connect the output sequence ReferenceEvapotranspiration of evap_v001 with the input sequence PET of lland_v2.

Additionally, lland_v2 requires temperature data itself for modelling snow processes, introducing the problem that we need to use the same data (the output of conv_v001) as the input of two differently named input sequences (AirTemperature and TemL for evap_v001 and lland_v2, respectively).

For our concrete example, we need to create two FusedVariable objects. E combines ReferenceEvapotranspiration and PET and T combines AirTemperature and TemL (for convenience, we import their globally available aliases):

>>> from hydpy import FusedVariable
>>> from hydpy.inputs import lland_PET, evap_AirTemperature, lland_TemL
>>> from hydpy.outputs import evap_ReferenceEvapotranspiration
>>> E = FusedVariable("E", evap_ReferenceEvapotranspiration, lland_PET)
>>> T = FusedVariable("T", evap_AirTemperature, lland_TemL)

Now we can construct the network:

• Node t1 handles the original temperature and serves as the input node to element conv. We define the (arbitrarily selected) string Temp to be its variable.

• Node e receives the potential evapotranspiration calculated by element evap and passes it to element lland. Node e thus receives the fused variable E.

• Node t2 handles the interpolated temperature and serves as the outlet node of element conv and the input node to elements evap and lland. Node t2 thus receives the fused variable T.

>>> from hydpy import Node, Element
>>> t1 = Node("t1", variable="Temp")
>>> t2 = Node("t2", variable=T)
>>> e = Node("e", variable=E)
>>> conv = Element("element_conv",
...                inlets=t1,
...                outlets=t2)
>>> evap = Element("element_evap",
...                inputs=t2,
...                outputs=e)
>>> lland = Element("element_lland",
...                 inputs=(t2, e),
...                 outlets="node_q")

Now we can prepare the different model objects and assign them to their corresponding elements (note that parameters InputCoordinates and OutputCoordinates of conv_v001 first require information on the location of the relevant nodes):

>>> from hydpy import prepare_model
>>> model_conv = prepare_model("conv_v001")
>>> model_conv.parameters.control.inputcoordinates(t1=(0, 0))
>>> model_conv.parameters.control.outputcoordinates(t2=(1, 1))
>>> model_conv.parameters.control.maxnmbinputs(1)
>>> model_conv.parameters.update()
>>> conv.model = model_conv
>>> evap.model = prepare_model("evap_v001")
>>> lland.model = prepare_model("lland_v2")

We assign a temperature value to node t1:

>>> t1.sequences.sim = -273.15

Model conv_v001 now can perform a simulation step and pass its output to node t2:

>>> conv.model.simulate(0)
>>> t2.sequences.sim
sim(-273.15)

Without further configuration, evap_v001 cannot perform any simulation steps. Hence, we just call its load_data() method to show that its input sequence AirTemperature is well connected to the Sim sequence of node t2 and receives the correct data:

>>> evap.model.load_data()
>>> evap.model.sequences.inputs.airtemperature
airtemperature(-273.15)

The output sequence ReferenceEvapotranspiration is also well connected. Calling method update_outputs() passes its (manually set) value to node e, respectively:

>>> evap.model.sequences.fluxes.referenceevapotranspiration = 999.9
>>> evap.model.update_outputs()
>>> e.sequences.sim
sim(999.9)

Finally, both input sequences TemL and PET receive the current values of nodes t2 and e:

>>> lland.model.load_data()
>>> lland.model.sequences.inputs.teml
teml(-273.15)
>>> lland.model.sequences.inputs.pet
pet(999.9)

When defining fused variables, class FusedVariable performs some registration behind the scenes, similar as classes Node and Element do. Again, the name works as the identifier, and we force the same fused variable to exist only once, even when defined in different selection files repeatedly. Hence, when we repeat the definition from above, we get the same object:

>>> Test = FusedVariable("T", evap_AirTemperature, lland_TemL)
>>> T is Test
True

Changing the member sequences of an existing fused variable is not allowed:

>>> from hydpy.inputs import hland_T
>>> FusedVariable("T", hland_T, lland_TemL)
Traceback (most recent call last):
...
ValueError: The sequences combined by a FusedVariable object cannot be changed.  The already defined sequences of the fused variable `T` are `evap_AirTemperature and lland_TemL` instead of `hland_T and lland_TemL`.  Keep in mind, that `name` is the unique identifier for fused variable instances.

Defining additional fused variables with the same member sequences does not seem advisable, but is allowed:

>>> Temp = FusedVariable("Temp", evap_AirTemperature, lland_TemL)
>>> T is Temp
False

To get an overview of the already existing fused variables, call method get_registry():

>>> len(FusedVariable.get_registry())
3

Principally, you can clear the registry via method clear_registry(), but remember it does not remove FusedVariable objects from the running process being otherwise referenced:

>>> FusedVariable.clear_registry()
>>> FusedVariable.get_registry()
()
>>> t2.variable
FusedVariable("T", evap_AirTemperature, lland_TemL)

classmethod get_registry() → Tuple[hydpy.core.devicetools.FusedVariable, …]

Get all FusedVariable objects initialised so far.

classmethod clear_registry() → None

Clear the registry from all FusedVariable objects initialised so far.

Use this method only for good reasons!

class hydpy.core.devicetools.Devices(*values: Optional[Union[DeviceType, str, Iterable[Union[DeviceType, str]]]], mutable: bool = True)

Bases: Generic[hydpy.core.devicetools.DeviceType]

Base class for class Elements and class Nodes.

The following features are common to class Nodes and class Elements. We arbitrarily select class Nodes for all examples.

To initialise a Nodes collection class, pass a variable number of str or Node objects. Strings are used to create new or query already existing nodes automatically:

>>> from hydpy import Node, Nodes
>>> nodes = Nodes("na",
...               Node("nb", variable="W"),
...               Node("nc", keywords=("group_a", "group_1")),
...               Node("nd", keywords=("group_a", "group_2")),
...               Node("ne", keywords=("group_b", "group_1")))

Nodes and Elements objects are containers supporting attribute access. You can access each node or element directly by its name:

>>> nodes.na
Node("na", variable="Q")

Wrong node names result in the following error message:

>>> nodes.wrong
Traceback (most recent call last):
...
AttributeError: The selected Nodes object has neither a `wrong` attribute nor does it handle a Node object with name or keyword `wrong`, which could be returned.

As explained in more detail in the documentation on property keywords, you can also use the keywords of the individual nodes to query the relevant ones:

>>> nodes.group_a
Nodes("nc", "nd")

Especially in this context, you might find it useful to also get an iterable object in case no node or only a single node is available:

>>> Nodes.forceiterable = True
>>> nodes.wrong
Nodes()
>>> nodes.na
Nodes("na")
>>> Nodes.forceiterable = False

Attribute deleting is supported:

>>> "na" in nodes
True
>>> del nodes.na
>>> "na" in nodes
False
>>> del nodes.na
Traceback (most recent call last):
...
AttributeError: The actual Nodes object does not handle a Node object named `na` which could be removed, and deleting other attributes is not supported.

However, shown by the next example, setting devices via attribute access could result in inconsistencies and is not allowed (see method add_device() instead):

>>> nodes.NF = Node("nf")
Traceback (most recent call last):
...
AttributeError: Setting attributes of Nodes objects could result in confusion whether a new attribute should be handled as a Node object or as a "normal" attribute and is thus not support, hence `NF` is rejected.

Nodes and Elements objects support iteration:

>>> len(nodes)
4
>>> for node in nodes:
...     print(node.name, end=",")
nb,nc,nd,ne,

The binary operators +, +=, - and -= support adding and removing single devices or groups of devices:

>>> nodes
Nodes("nb", "nc", "nd", "ne")
>>> nodes - Node("nc")
Nodes("nb", "nd", "ne")

Nodes(“nb”, “nc”, “nd”, “ne”) >>> nodes -= Nodes(“nc”, “ne”) >>> nodes Nodes(“nb”, “nd”)

>>> nodes + "nc"
Nodes("nb", "nc", "nd")
>>> nodes
Nodes("nb", "nd")
>>> nodes += ("nc", Node("ne"))
>>> nodes
Nodes("nb", "nc", "nd", "ne")

Attempts to add already existing or to remove non-existing devices do no harm:

>>> nodes
Nodes("nb", "nc", "nd", "ne")
>>> nodes + ("nc", "ne")
Nodes("nb", "nc", "nd", "ne")
>>> nodes - Node("na")
Nodes("nb", "nc", "nd", "ne")

Comparisons are supported, with “x < y” being True, if “x” is a subset of “y”:

>>> subgroup = Nodes("nc", "ne")
>>> subgroup < nodes, nodes < subgroup, nodes < nodes
(True, False, False)
>>> subgroup <= nodes, nodes <= subgroup, nodes <= nodes
(True, False, True)
>>> subgroup == nodes, nodes == subgroup, nodes == nodes, nodes == "nodes"
(False, False, True, False)
>>> subgroup != nodes, nodes != subgroup, nodes != nodes, nodes != "nodes"
(True, True, False, True)
>>> subgroup >= nodes, nodes >= subgroup, nodes >= nodes
(False, True, True)
>>> subgroup > nodes, nodes > subgroup, nodes > nodes
(False, True, False)

Passing wrong arguments to the constructor of class Node results in errors like the following:

>>> from hydpy import Element
>>> Nodes("na", Element("ea"))
Traceback (most recent call last):
...
TypeError: While trying to initialise a `Nodes` object, the following error occurred: The given (sub)value `Element("ea")` is not an instance of the following classes: Node and str.

mutable: bool

forceiterable: bool = False

abstract static get_contentclass() → Type

To be overridden.

add_device(device: Union[DeviceType, str]) → None

Add the given Node or Element object to the actual Nodes or Elements object.

You can pass either a string or a device:

>>> from hydpy import Nodes
>>> nodes = Nodes()
>>> nodes.add_device("old_node")
>>> nodes
Nodes("old_node")
>>> nodes.add_device("new_node")
>>> nodes
Nodes("new_node", "old_node")

Method add_device() is disabled for immutable Nodes and Elements objects:

>>> nodes.mutable = False
>>> nodes.add_device("newest_node")
Traceback (most recent call last):
...
RuntimeError: While trying to add the device `newest_node` to a Nodes object, the following error occurred: Adding devices to immutable Nodes objects is not allowed.

remove_device(device: Union[DeviceType, str]) → None

Remove the given Node or Element object from the actual Nodes or Elements object.

You can pass either a string or a device:

>>> from hydpy import Node, Nodes
>>> nodes = Nodes("node_x", "node_y")
>>> node_x, node_y = nodes
>>> nodes.remove_device(Node("node_y"))
>>> nodes
Nodes("node_x")
>>> nodes.remove_device(Node("node_x"))
>>> nodes
Nodes()
>>> nodes.remove_device(Node("node_z"))
Traceback (most recent call last):
...
ValueError: While trying to remove the device `node_z` from a Nodes object, the following error occurred: The actual Nodes object does not handle such a device.

Method remove_device() is disabled for immutable Nodes and Elements objects:

>>> nodes.mutable = False
>>> nodes.remove_device("node_z")
Traceback (most recent call last):
...
RuntimeError: While trying to remove the device `node_z` from a Nodes object, the following error occurred: Removing devices from immutable Nodes objects is not allowed.

property names

A sorted tuple of the names of the handled devices.

>>> from hydpy import Nodes
>>> Nodes("a", "c", "b").names
('a', 'b', 'c')

property devices

A tuple of the handled devices sorted by the device names.

>>> from hydpy import Nodes
>>> for node in Nodes("a", "c", "b").devices:
...     print(repr(node))
Node("a", variable="Q")
Node("b", variable="Q")
Node("c", variable="Q")

property keywords

A set of all keywords of all handled devices.

In addition to attribute access via device names, Nodes and Elements objects allow for attribute access via keywords, allowing for an efficient search of certain groups of devices. Let us use the example from above, where the nodes na and nb have no keywords, but each of the other three nodes both belongs to either group_a or group_b and group_1 or group_2:

>>> from hydpy import Node, Nodes
>>> nodes = Nodes("na",
...               Node("nb", variable="W"),
...               Node("nc", keywords=("group_a", "group_1")),
...               Node("nd", keywords=("group_a", "group_2")),
...               Node("ne", keywords=("group_b", "group_1")))
>>> nodes
Nodes("na", "nb", "nc", "nd", "ne")
>>> sorted(nodes.keywords)
['group_1', 'group_2', 'group_a', 'group_b']

If you are interested in inspecting all devices belonging to group_a, select them via this keyword:

>>> subgroup = nodes.group_1
>>> subgroup
Nodes("nc", "ne")

You can further restrict the search by also selecting the devices belonging to group_b, which holds only for node “e”, in the given example:

>>> subsubgroup = subgroup.group_b
>>> subsubgroup
Node("ne", variable="Q",
     keywords=["group_1", "group_b"])

Note that the keywords already used for building a device subgroup are not informative anymore (as they hold for each device) and are thus not shown anymore:

>>> sorted(subgroup.keywords)
['group_a', 'group_b']

The latter might be confusing if you intend to work with a device subgroup for a longer time. After copying the subgroup, all keywords of the contained devices are available again:

>>> from copy import copy
>>> newgroup = copy(subgroup)
>>> sorted(newgroup.keywords)
['group_1', 'group_a', 'group_b']

search_keywords(*keywords: str) → DevicesTypeBound

Search for all devices handling at least one of the given keywords and return them.

>>> from hydpy import Node, Nodes
>>> nodes = Nodes("na",
...               Node("nb", variable="W"),
...               Node("nc", keywords=("group_a", "group_1")),
...               Node("nd", keywords=("group_a", "group_2")),
...               Node("ne", keywords=("group_b", "group_1")))
>>> nodes.search_keywords("group_c")
Nodes()
>>> nodes.search_keywords("group_a")
Nodes("nc", "nd")
>>> nodes.search_keywords("group_a", "group_1")
Nodes("nc", "nd", "ne")

open_files(idx: int = 0) → None

Call method open_files() or open_files() of all contained Node or Element objects.

close_files() → None

Call method close_files() or close_files() of all contained Node or Element objects.

copy() → DevicesTypeBound

Return a shallow copy of the actual Nodes or Elements object.

Method copy() returns a semi-flat copy of Nodes or Elements objects, due to their devices being not copyable:

>>> from hydpy import Nodes
>>> old = Nodes("x", "y")
>>> import copy
>>> new = copy.copy(old)
>>> new == old
True
>>> new is old
False
>>> new.devices is old.devices
False
>>> new.x is new.x
True

Changing the name of a device is recognised both by the original and the copied collection objects:

>>> new.x.name = "z"
>>> old.z
Node("z", variable="Q")
>>> new.z
Node("z", variable="Q")

Deep copying is permitted due to the above reason:

>>> copy.deepcopy(old)
Traceback (most recent call last):
...
NotImplementedError: Deep copying of Nodes objects is not supported, as it would require to make deep copies of the Node objects themselves, which is in conflict with using their names as identifiers.

intersection(*other: DeviceType) → DevicesTypeBound

Return the intersection with the given Devices object.

>>> from hydpy import Node, Nodes
>>> nodes1 = Nodes("na", "nb", "nc")
>>> nodes2 = Nodes("na", "nc", "nd")
>>> nodes1.intersection(*nodes2)
Nodes("na", "nc")

assignrepr(prefix: str = '') → str

Return a repr() string with a prefixed assignment.

class hydpy.core.devicetools.Nodes(*values: Optional[Union[DeviceType, str, Iterable[Union[DeviceType, str]]]], mutable: bool = True)

Bases: hydpy.core.devicetools.Devices[Node]

A container class for handling Node objects.

For the general usage of Nodes objects, please see the documentation on its base class Devices.

static get_contentclass() → Type[hydpy.core.devicetools.Node]

Return class Node.

prepare_allseries(ramflag: bool = True) → None

Call methods prepare_simseries() and prepare_obsseries().

prepare_simseries(ramflag: bool = True) → None

Call method prepare_simseries() of all handled Node objects.

prepare_obsseries(ramflag: bool = True) → None

Call method prepare_obsseries() of all handled Node objects.

load_allseries() → None

Call methods load_simseries() and load_obsseries().

load_simseries() → None

Call method load_ext() of all Sim objects with an activated memoryflag.

load_obsseries() → None

Call method load_ext() of all Obs objects with an activated memoryflag.

save_allseries() → None

Call methods save_simseries() and save_obsseries().

save_simseries() → None

Call method save_ext() of all Sim objects with an activated memoryflag.

save_obsseries() → None

Call method save_ext() of all Obs objects with an activated memoryflag.

property variables

Return a set of the variables of all handled Node objects.

>>> from hydpy import Node, Nodes
>>> nodes = Nodes(Node("x1"),
...               Node("x2", variable="Q"),
...               Node("x3", variable="H"))
>>> sorted(nodes.variables)
['H', 'Q']

mutable: bool

class hydpy.core.devicetools.Elements(*values: Optional[Union[DeviceType, str, Iterable[Union[DeviceType, str]]]], mutable: bool = True)

Bases: hydpy.core.devicetools.Devices[Element]

A container for handling Element objects.

For the general usage of Elements objects, please see the documentation on its base class Devices.

static get_contentclass() → Type[hydpy.core.devicetools.Element]

Return class Element.

prepare_models() → None

Call method prepare_model() of all handle Element objects.

We show, based the LahnH example project, that method init_model() prepares the Model objects of all elements, including building the required connections and updating the derived parameters:

>>> from hydpy.examples import prepare_full_example_1
>>> prepare_full_example_1()
>>> from hydpy import attrready, HydPy, pub, TestIO
>>> with TestIO():
...     hp = HydPy("LahnH")
...     pub.timegrids = "1996-01-01", "1996-02-01", "1d"
...     hp.prepare_network()
...     hp.prepare_models()
>>> hp.elements.land_dill.model.parameters.derived.dt
dt(0.000833)

Wrong control files result in error messages like the following:

>>> with TestIO():
...     with open("LahnH/control/default/land_dill.py", "a") as file_:
...         _ = file_.write("zonetype(-1)")
...     hp.prepare_models()   
Traceback (most recent call last):
...
ValueError: While trying to initialise the model object of element `land_dill`, the following error occurred: While trying to load the control file `...land_dill.py`, the following error occurred: At least one value of parameter `zonetype` of element `?` is not valid.

By default, missing control files result in exceptions:

>>> del hp.elements.land_dill.model
>>> import os
>>> with TestIO():
...     os.remove("LahnH/control/default/land_dill.py")
...     hp.prepare_models()   
Traceback (most recent call last):
...
FileNotFoundError: While trying to initialise the model object of element `land_dill`, the following error occurred: While trying to load the control file `...land_dill.py`, the following error occurred: ...
>>> attrready(hp.elements.land_dill, "model")
False

When building new, still incomplete HydPy projects, this behaviour can be annoying. After setting the option warnmissingcontrolfile to False, missing control files only result in a warning:

>>> with TestIO():
...     with pub.options.warnmissingcontrolfile(True):
...         hp.prepare_models()
Traceback (most recent call last):
...
UserWarning: Due to a missing or no accessible control file, no model could be initialised for element `land_dill`
>>> attrready(hp.elements.land_dill, "model")
False

init_models() → None

Deprecated: use method prepare_models() instead.

>>> from hydpy import Elements
>>> from unittest import mock
>>> with mock.patch.object(Elements, "prepare_models") as mocked:
...     elements = Elements()
...     elements.init_models()
Traceback (most recent call last):
...
hydpy.core.exceptiontools.HydPyDeprecationWarning: Method `init_models` of class `Elements` is deprecated.  Use method `prepare_models` instead.
>>> mocked.call_args_list
[call()]

save_controls(parameterstep: Optional[timetools.PeriodConstrArg] = None, simulationstep: Optional[timetools.PeriodConstrArg] = None, auxfiler: Optional[auxfiletools.Auxfiler] = None)

Save the control parameters of the Model object handled by each Element object and eventually the ones handled by the given Auxfiler object.

load_conditions() → None

Save the initial conditions of the Model object handled by each Element object.

save_conditions() → None

Save the calculated conditions of the Model object handled by each Element object.

trim_conditions() → None

Call method trim_conditions() of the Sequences object handled (indirectly) by each Element object.

reset_conditions() → None

Call method reset() of the Sequences object handled (indirectly) by each Element object.

property conditions

A nested dictionary containing the values of all ConditionSequence objects of all currently handled models.

See the documentation on property conditions for further information.

prepare_allseries(ramflag: bool = True) → None

Call method prepare_allseries() of all handled Element objects.

prepare_inputseries(ramflag: bool = True) → None

Call method prepare_inputseries() of all handled Element objects.

prepare_fluxseries(ramflag: bool = True) → None

Call method prepare_fluxseries() of all handled Element objects.

prepare_stateseries(ramflag: bool = True) → None

Call method prepare_stateseries() of all handled Element objects.

load_allseries() → None

Call methods load_inputseries(), load_fluxseries(), and load_stateseries().

load_inputseries() → None

Call method load_ext() of all InputSequence objects with an activated memoryflag.

load_fluxseries() → None

Call method load_ext() of all FluxSequence objects with an activated memoryflag.

load_stateseries() → None

Call method load_ext() of all StateSequence objects with an activated memoryflag.

save_allseries() → None

Call methods save_inputseries(), save_fluxseries(), and save_stateseries().

save_inputseries() → None

Call method save_ext() of all InputSequence objects with an activated memoryflag.

save_fluxseries() → None

Call method save_ext() of all FluxSequence objects with an activated memoryflag.

save_stateseries() → None

Call method save_ext() of all StateSequence objects with an activated memoryflag.

mutable: bool

class hydpy.core.devicetools.Device(value, *args, **kwargs)

Bases: Generic[hydpy.core.devicetools.DevicesTypeUnbound]

Base class for class Element and class Node.

abstract classmethod get_handlerclass() → Type

To be overridden.

classmethod query_all() → DevicesTypeUnbound

Get all Node or Element objects initialised so far.

See the main documentation on module devicetools for further information.

classmethod extract_new() → DevicesTypeUnbound

Gather all “new” Node or Element objects.

See the main documentation on module devicetools for further information.

classmethod clear_all() → None

Clear the registry from all initialised Node or Element objects.

See the main documentation on module devicetools for further information.

property name

Name of the actual Node or Element object.

Device names serve as identifiers, as explained in the main documentation on module devicetools. So define them carefully:

>>> from hydpy import Node
>>> Node.clear_all()
>>> node1, node2 = Node("n1"), Node("n2")
>>> node1 is Node("n1")
True
>>> node1 is Node("n2")
False

Each device name must be a valid variable identifier (see function valid_variable_identifier()), to allow for attribute access:

>>> from hydpy import Nodes
>>> nodes = Nodes(node1, "n2")
>>> nodes.n1
Node("n1", variable="Q")

Invalid variable identifiers result in errors like the following:

>>> node3 = Node("n 3")   
Traceback (most recent call last):
...
ValueError: While trying to initialize a `Node` object with value `n 3` of type `str`, the following error occurred: The given name string `n 3` does not define a valid variable identifier.  ...

When you change the name of a device (only do this for a good reason), the corresponding keys of all related Nodes and Elements objects (as well as of the internal registry) change automatically:

>>> Node.query_all()
Nodes("n1", "n2")
>>> node1.name = "n1a"
>>> nodes
Nodes("n1a", "n2")
>>> Node.query_all()
Nodes("n1a", "n2")

property keywords

Keywords describing the actual Node or Element object.

The keywords are contained within a Keywords object:

>>> from hydpy import Node
>>> node = Node("n", keywords="word0")
>>> node.keywords
Keywords("word0")

Assigning new words does not overwrite already existing ones. You are allowed to add them individually or within iterable objects:

>>> node.keywords = "word1"
>>> node.keywords = "word2", "word3"
>>> node.keywords
Keywords("word0", "word1", "word2", "word3")

Additionally, passing additional keywords to the constructor of class Node or Element works also fine:

>>> Node("n", keywords=("word3", "word4", "word5"))
Node("n", variable="Q",
     keywords=["word0", "word1", "word2", "word3", "word4", "word5"])

You can delete all keywords at once:

>>> del node.keywords
>>> node.keywords
Keywords()

class hydpy.core.devicetools.Node(value, *args, **kwargs)

Bases: hydpy.core.devicetools.Device[hydpy.core.devicetools.Nodes]

Handles the data flow between Element objects.

Node objects always handle two sequences, a Sim object for simulated values and an Obs object for measured values:

>>> from hydpy import Node
>>> node = Node("test")
>>> for sequence in node.sequences:
...     print(sequence)
sim(0.0)
obs(0.0)

Each node can handle an arbitrary number of “input” and “output” elements, available as instance attributes entries and exits, respectively:

>>> node.entries
Elements()
>>> node.exits
Elements()

You cannot (or at least should not) add new elements manually:

>>> node.entries = "element"
Traceback (most recent call last):
...
AttributeError: can't set attribute
>>> node.exits.add_device("element")
Traceback (most recent call last):
...
RuntimeError: While trying to add the device `element` to a Elements object, the following error occurred: Adding devices to immutable Elements objects is not allowed.

Instead, see the documentation on class Element on how to connect Node and Element objects properly.

masks = defaultmask of module hydpy.core.masktools

sequences: hydpy.core.sequencetools.NodeSequences

classmethod get_handlerclass() → Type[hydpy.core.devicetools.Nodes]

Return class Nodes.

property entries

Group of Element objects which set the the simulated value of the Node object.

property exits

Group of Element objects which query the simulated or observed value of the actual Node object.

property variable

The variable handled by the actual Node object.

By default, we suppose that nodes route discharge:

>>> from hydpy import Node
>>> node = Node("test1")
>>> node.variable
'Q'

Each other string, as well as each InputSequence subclass, is acceptable (for further information see the documentation on method connect()):

>>> Node("test2", variable="H")
Node("test2", variable="H")
>>> from hydpy.models.hland.hland_inputs import T
>>> Node("test3", variable=T)
Node("test3", variable=hland_T)

The last above example shows that the string representations of nodes handling “class variables” use the aliases importable from the top-level of the HydPy package:

>>> from hydpy.inputs import hland_P
>>> Node("test4", variable=hland_P)
Node("test4", variable=hland_P)

For some complex HydPy projects, one may need to fall back on FusedVariable objects. The string representation then relies on the name of the fused variable:

>>> from hydpy import FusedVariable
>>> from hydpy.inputs import lland_Nied
>>> Precipitation = FusedVariable("Precip", hland_P, lland_Nied)
>>> Node("test5", variable=Precipitation)
Node("test5", variable=Precip)

To avoid confusion, one cannot change property variable:

>>> node.variable = "H"
Traceback (most recent call last):
...
AttributeError: can't set attribute
>>> Node("test1", variable="H")
Traceback (most recent call last):
...
ValueError: The variable to be represented by a Node instance cannot be changed.  The variable of node `test1` is `Q` instead of `H`.  Keep in mind, that `name` is the unique identifier of node objects.

property deploymode

Defines the kind of information a node offers its exit elements.

HydPy supports the following modes:

• newsim: Deploy the simulated values calculated just recently. newsim is the default mode, used, for example, when a node receives a discharge value from an upstream element and passes it to the downstream element directly.

• obs: Deploy observed values instead of simulated values. The node still receives the simulated values from its upstream element(s). However, it deploys values to its downstream element(s), which are defined externally. Usually, these values are observations made available within a time-series file. See the documentation on module sequencetools for further information on file specifications.

• oldsim: Similar to mode obs. However, it is usually applied when a node is supposed to deploy simulated values which have been calculated in a previous simulation run and stored in a sequence file.

• obs_newsim: Combination of mode obs and newsim. Mode obs_newsim gives priority to the provision of observation values. New simulation values serve as a replacement for missing observed values.

• obs_oldsim: Combination of mode obs and oldsim. Mode obs_oldsim gives priority to the provision of observation values. Old simulation values serve as a replacement for missing observed values.

One relevant difference between modes obs and oldsim is that the external values are either handled by the obs or the sim sequence object. Hence, if you select the oldsim mode, the values of the upstream elements calculated within the current simulation are not available (e.g. for parameter calibration) after the simulation finishes.

Please refer to the documentation on method simulate() of class HydPy, which provides for some application examples.

>>> from hydpy import Node
>>> node = Node("test")
>>> node.deploymode
'newsim'
>>> node.deploymode = "obs"
>>> node.deploymode
'obs'
>>> node.deploymode = "oldsim"
>>> node.deploymode
'oldsim'
>>> node.deploymode = "obs_newsim"
>>> node.deploymode
'obs_newsim'
>>> node.deploymode = "obs_oldsim"
>>> node.deploymode
'obs_oldsim'
>>> node.deploymode = "newsim"
>>> node.deploymode
'newsim'
>>> node.deploymode = "oldobs"
Traceback (most recent call last):
...
ValueError: When trying to set the routing mode of node `test`, the value `oldobs` was given, but only the following values are allowed: `newsim`, `oldsim`, `obs`, `obs_newsim`, and `obs_oldsim`.

get_double(group: str) → hydpy.cythons.autogen.pointerutils.Double

Return the Double object appropriate for the given Element input or output group and the actual deploymode.

Method get_double() should be of interest for framework developers only (and eventually for model developers).

Let Node object node1 handle different simulation and observation values:

>>> from hydpy import Node
>>> node = Node("node1")
>>> node.sequences.sim = 1.0
>>> node.sequences.obs = 2.0

The following test function shows for a given deploymode if method get_double() either returns the Double object handling the simulated value (1.0) or the Double object handling the observed value (2.0):

>>> def test(deploymode):
...     node.deploymode = deploymode
...     for group in ("inlets", "receivers", "outlets", "senders"):
...         print(group, node.get_double(group))

In the default mode, nodes (passively) route simulated values through offering the Double object of sequence Sim to all Element input and output groups:

>>> test("newsim")
inlets 1.0
receivers 1.0
outlets 1.0
senders 1.0

Setting deploymode to obs means that a node receives simulated values (from group outlets or senders), but provides observed values (to group inlets or receivers):

>>> test("obs")
inlets 2.0
receivers 2.0
outlets 1.0
senders 1.0

With deploymode set to oldsim, the node provides (previously) simulated values (to group inlets or receivers) but does not receive any values. Method get_double() just returns a dummy Double object with value 0.0 in this case (for group outlets or senders):

>>> test("oldsim")
inlets 1.0
receivers 1.0
outlets 0.0
senders 0.0

Other Element input or output groups are not supported:

>>> node.get_double("test")
Traceback (most recent call last):
...
ValueError: Function `get_double` of class `Node` does not support the given group name `test`.

reset(idx: int = 0) → None

Reset the actual value of the simulation sequence to zero.

>>> from hydpy import Node
>>> node = Node("node1")
>>> node.sequences.sim = 1.0
>>> node.reset()
>>> node.sequences.sim
sim(0.0)

open_files(idx: int = 0) → None

Call method open_files() of the Sequences object handled by the actual Node object.

close_files() → None

Call method close_files() of the Sequences object handled by the actual Node object.

prepare_allseries(ramflag: bool = True) → None

Prepare the series object both of the Sim and the Obs sequence.

Call this method before a simulation run if you need access to the whole time-series of the simulated and the observed series after the simulation run is finished.

By default, the time-series are stored in RAM, which is the faster option. If your RAM is limited, pass False to function argument ramflag to store the series on disk.

prepare_simseries(ramflag: bool = True) → None

Prepare the series object of the Sim sequence.

See method prepare_allseries() for further information.

prepare_obsseries(ramflag: bool = True) → None

Prepare the series object of the Obs sequence.

See method prepare_allseries() for further information.

plot_allseries(*, labels: Optional[Tuple[str, str]] = None, colors: Optional[Union[str, Tuple[str, str]]] = None, linestyles: Optional[Union[typing_extensions.Literal[-, --, -., :, solid, dashed, dashdot, dotted], Tuple[typing_extensions.Literal[-, --, -., :, solid, dashed, dashdot, dotted], typing_extensions.Literal[-, --, -., :, solid, dashed, dashdot, dotted]]]] = None, linewidths: Optional[Union[int, Tuple[int, int]]] = None, focus: bool = False, stepsize: Optional[typing_extensions.Literal[daily, d, monthly, m]] = None) → matplotlib.figure.Figure

Plot the series data of both the Sim and the Obs sequence object.

We demonstrate the functionalities of method plot_allseries() based on the Lahn example project:

>>> from hydpy.examples import prepare_full_example_2
>>> hp, pub, _ = prepare_full_example_2(lastdate="1997-01-01")

We perform a simulation run and calculate “observed” values for node dill:

>>> hp.simulate()
>>> dill = hp.nodes.dill
>>> dill.sequences.obs.series = dill.sequences.sim.series + 10.0

Calling method plot_allseries() prints the time-series of both sequences to the screen immediately (if not, you need to activate the interactive mode of matplotlib first):

>>> figure = dill.plot_allseries()

Subsequent calls to plot_allseries() or the related methods plot_simseries() and plot_obsseries() of nodes add further time-series data to the existing plot:

>>> lahn_1 = hp.nodes.lahn_1
>>> figure = lahn_1.plot_simseries()

You can modify the appearance of the lines by passing different arguments:

>>> lahn_1.sequences.obs.series = lahn_1.sequences.sim.series + 10.0
>>> figure = lahn_1.plot_obsseries(color="black", linestyle="dashed")

All mentioned plotting functions return a matplotlib Figure object. Use it to for further plot handling, e.g. for adding a title and saving the current figure to disk:

>>> from hydpy.core.testtools import save_autofig
>>> text = figure.axes[0].set_title('daily')
>>> save_autofig("Node_plot_allseries_1.png", figure)

You can plot the data in an aggregated manner (see the documentation on function aggregate_series() for the supported step sizes and further details):

>>> figure = dill.plot_allseries(stepsize="monthly")
>>> text = figure.axes[0].set_title('monthly')
>>> save_autofig("Node_plot_allseries_2.png", figure)

You can restrict the plotted period via the eval_ Timegrid and overwrite the time-series label and other defaults via keyword arguments. For tuples passed to method plot_allseries(), the first entry corresponds to the observation and the second one to the simulation results:

>>> pub.timegrids.eval_.dates = "1996-10-01", "1996-11-01"
>>> figure = lahn_1.plot_allseries(labels=("measured", "calculated"),
...                                colors=("blue", "red"),
...                                linewidths=2,
...                                linestyles=("--", ":"),
...                                focus=True,)
>>> save_autofig("Node_plot_allseries_3.png", figure)

When necessary, all plotting methods raise errors like the following:

>>> figure = lahn_1.plot_allseries(stepsize="quaterly")
Traceback (most recent call last):
...
ValueError: While trying to plot the time series of sequence(s) obs and sim of node `lahn_1` for the period `1996-10-01 00:00:00` to `1996-11-01 00:00:00`, the following error occurred: While trying to aggregate the given series, the following error occurred: Argument `stepsize` received value `quaterly`, but only the following ones are supported: `monthly` (default) and `daily`.

>>> from hydpy import pub
>>> del pub.timegrids
>>> figure = lahn_1.plot_allseries()
Traceback (most recent call last):
...
hydpy.core.exceptiontools.AttributeNotReady: While trying to plot the time series of sequence(s) obs and sim of node `lahn_1` , the following error occurred: Attribute timegrids of module `pub` is not defined at the moment.

plot_simseries(*, label: Optional[str] = None, color: Optional[str] = None, linestyle: Optional[typing_extensions.Literal[-, --, -., :, solid, dashed, dashdot, dotted]] = None, linewidth: Optional[int] = None, focus: bool = False, stepsize: Optional[typing_extensions.Literal[daily, d, monthly, m]] = None) → matplotlib.figure.Figure

Plot the series of the Sim sequence object.

See method plot_allseries() for further information.

plot_obsseries(*, label: Optional[str] = None, color: Optional[str] = None, linestyle: Optional[typing_extensions.Literal[-, --, -., :, solid, dashed, dashdot, dotted]] = None, linewidth: Optional[int] = None, focus: bool = False, stepsize: Optional[typing_extensions.Literal[daily, d, monthly, m]] = None) → matplotlib.figure.Figure

Plot the series of the Obs sequence object.

See method plot_allseries() for further information.

assignrepr(prefix: str = '') → str

Return a repr() string with a prefixed assignment.

class hydpy.core.devicetools.Element(value, *args, **kwargs)

Bases: hydpy.core.devicetools.Device[hydpy.core.devicetools.Elements]

Handles a Model object and connects it to other models via

Node objects.

When preparing Element objects one links them to nodes of different “groups”, each group of nodes implemented as an immutable Nodes object:

• inlets and outlets nodes handle, for example, the inflow to and the outflow from the respective element.

• receivers and senders nodes are thought for information flow between arbitrary elements, for example, to inform a dam model about the discharge at a gauge downstream.

• inputs nodes provide optional input information, for example, interpolated precipitation that could alternatively be read from files as well.

• outputs nodes query optional output information, for example, the water level of a dam.

You can select the relevant nodes either by passing them explicitly or through passing their name both as single objects or as objects contained within an iterable object:

>>> from hydpy import Element, Node
>>> Element("test",
...         inlets="inl1",
...         outlets=Node("outl1"),
...         receivers=("rec1", Node("rec2")))
Element("test",
        inlets="inl1",
        outlets="outl1",
        receivers=["rec1", "rec2"])

Repeating such a statement with different nodes adds them to the existing ones without any conflict in case of repeated specifications:

>>> Element("test",
...         inlets="inl1",
...         receivers=("rec2", "rec3"),
...         senders="sen1",
...         inputs="inp1",
...         outputs="outp1")
Element("test",
        inlets="inl1",
        outlets="outl1",
        receivers=["rec1", "rec2", "rec3"],
        senders="sen1",
        inputs="inp1",
        outputs="outp1")

Subsequent adding of nodes also works via property access:

>>> test = Element("test")
>>> test.inlets = "inl2"
>>> test.outlets = None
>>> test.receivers = ()
>>> test.senders = "sen2", Node("sen3")
>>> test.inputs = []
>>> test.outputs = Node("outp2")
>>> test
Element("test",
        inlets=["inl1", "inl2"],
        outlets="outl1",
        receivers=["rec1", "rec2", "rec3"],
        senders=["sen1", "sen2", "sen3"],
        inputs="inp1",
        outputs=["outp1", "outp2"])

The properties try to verify that all connections make sense. For example, an element should never handle an inlet node that it also handles as an outlet, input, or output node:

>>> test.inlets = "outl1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given inlet node `outl1` is already defined as a(n) outlet node, which is not allowed.

>>> test.inlets = "inp1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given inlet node `inp1` is already defined as a(n) input node, which is not allowed.

>>> test.inlets = "outp1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given inlet node `outp1` is already defined as a(n) output node, which is not allowed.

Similar holds for the outlet nodes:

>>> test.outlets = "inl1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given outlet node `inl1` is already defined as a(n) inlet node, which is not allowed.

>>> test.outlets = "inp1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given outlet node `inp1` is already defined as a(n) input node, which is not allowed.

>>> test.outlets = "outp1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given outlet node `outp1` is already defined as a(n) output node, which is not allowed.

The following restrictions hold for the sender nodes:

>>> test.senders = "rec1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given sender node `rec1` is already defined as a(n) receiver node, which is not allowed.

>>> test.senders = "inp1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given sender node `inp1` is already defined as a(n) input node, which is not allowed.

>>> test.senders = "outp1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given sender node `outp1` is already defined as a(n) output node, which is not allowed.

The following restrictions hold for the receiver nodes:

>>> test.receivers = "sen1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given receiver node `sen1` is already defined as a(n) sender node, which is not allowed.

>>> test.receivers = "inp1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given receiver node `inp1` is already defined as a(n) input node, which is not allowed.

>>> test.receivers = "outp1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given receiver node `outp1` is already defined as a(n) output node, which is not allowed.

The following restrictions hold for the input nodes:

>>> test.inputs = "outp1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given input node `outp1` is already defined as a(n) output node, which is not allowed.

>>> test.inputs = "inl1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given input node `inl1` is already defined as a(n) inlet node, which is not allowed.

>>> test.inputs = "outl1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given input node `outl1` is already defined as a(n) outlet node, which is not allowed.

>>> test.inputs = "sen1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given input node `sen1` is already defined as a(n) sender node, which is not allowed.

>>> test.inputs = "rec1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given input node `rec1` is already defined as a(n) receiver node, which is not allowed.

The following restrictions hold for the output nodes:

>>> test.outputs = "inp1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given output node `inp1` is already defined as a(n) input node, which is not allowed.

>>> test.outputs = "inl1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given output node `inl1` is already defined as a(n) inlet node, which is not allowed.

>>> test.outputs = "outl1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given output node `outl1` is already defined as a(n) outlet node, which is not allowed.

>>> test.outputs = "sen1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given output node `sen1` is already defined as a(n) sender node, which is not allowed.

>>> test.outputs = "rec1"
Traceback (most recent call last):
...
ValueError: For element `test`, the given output node `rec1` is already defined as a(n) receiver node, which is not allowed.

Note that the discussed Nodes objects are immutable by default, disallowing to change them in other ways as described above:

>>> test.inlets += "inl3"
Traceback (most recent call last):
...
RuntimeError: While trying to add the device `inl3` to a Nodes object, the following error occurred: Adding devices to immutable Nodes objects is not allowed.

Setting their mutable flag to True changes this behaviour:

>>> test.inlets.mutable = True
>>> test.inlets.add_device("inl3")

However, then it is up to you to make sure that the added node also handles the relevant element in the suitable group. In the given example, only node inl2 has been added properly but not node inl3:

>>> test.inlets.inl2.exits
Elements("test")
>>> test.inlets.inl3.exits
Elements()

property inlets

Group of Node objects from which the handled Model object queries its “upstream” input values (e.g. inflow).

property outlets

Group of Node objects to which the handled Model object passes its “downstream” output values (e.g. outflow).

property receivers

Group of Node objects from which the handled Model object queries its “remote” information values (e.g. discharge at a remote downstream).

property senders

Group of Node objects to which the handled Model object passes its “remote” information values (e.g. water level of a dam model).

property inputs

Group of Node objects from which the handled Model object queries its “external” input values, instead of reading them from files (e.g. interpolated precipitation).

property outputs

Group of Node objects to which the handled Model object passes its “internal” output values, available via sequences of type FluxSequence or StateSequence (e.g. potential evaporation).

classmethod get_handlerclass() → Type[hydpy.core.devicetools.Elements]

Return class Elements.

property model

The Model object handled by the actual Element object.

Directly after their initialisation, elements do not know which model they require:

>>> from hydpy import attrready, Element
>>> hland = Element("hland", outlets="outlet")
>>> hland.model
Traceback (most recent call last):
...
hydpy.core.exceptiontools.AttributeNotReady: The model object of element `hland` has been requested but not been prepared so far.

During scripting and when working interactively in the Python shell, it is often convenient to assign a Model directly.

>>> from hydpy.models.hland_v1 import *
>>> parameterstep("1d")
>>> hland.model = model
>>> hland.model.name
'hland_v1'

>>> del hland.model
>>> attrready(hland, "model")
False

For the “usual” approach to prepare models, please see the method prepare_model().

The following examples show that assigning Model objects to property model creates some connection required by the respective model type automatically . These examples should be relevant for developers only.

The following hbranch model branches a single input value (from to node inp) to multiple outputs (nodes out1 and out2):

>>> from hydpy import Element, Node, reverse_model_wildcard_import
>>> reverse_model_wildcard_import()
>>> element = Element("a_branch",
...                   inlets="branch_input",
...                   outlets=("branch_output_1", "branch_output_2"))
>>> inp = element.inlets.branch_input
>>> out1, out2 = element.outlets
>>> from hydpy.models.hbranch import *
>>> parameterstep()
>>> xpoints(0.0, 3.0)
>>> ypoints(branch_output_1=[0.0, 1.0], branch_output_2=[0.0, 2.0])
>>> parameters.update()
>>> element.model = model

To show that the inlet and outlet connections are built properly, we assign a new value to the inlet node inp and verify that the suitable fractions of this value are passed to the outlet nodes out1` and out2 by calling method simulate():

>>> inp.sequences.sim = 999.0
>>> model.simulate(0)
>>> fluxes.input
input(999.0)
>>> out1.sequences.sim
sim(333.0)
>>> out2.sequences.sim
sim(666.0)

prepare_model(clear_registry: bool = True) → None

Load the control file of the actual Element object, initialise its Model object, build the required connections via (an eventually overridden version of) method connect() of class Model, and update its derived parameter values via calling (an eventually overridden version) of method update() of class Parameters.

See method prepare_models() of class HydPy and property Model of class Element fur further information.

init_model(clear_registry: bool = True) → None

Deprecated: use method prepare_model() instead.

>>> from hydpy import Element
>>> from unittest import mock
>>> with mock.patch.object(Element, "prepare_model") as mocked:
...     element = Element("test")
...     element.init_model(False)
Traceback (most recent call last):
...
hydpy.core.exceptiontools.HydPyDeprecationWarning: Method `init_model` of class `Element` is deprecated.  Use method `prepare_model` instead.
>>> mocked.call_args_list
[call(False)]

property variables

A set of all different variable values of the Node objects directly connected to the actual Element object.

Suppose there is an element connected to five nodes, which (partly) represent different variables:

>>> from hydpy import Element, Node
>>> element = Element("Test",
...                   inlets=(Node("N1", "X"), Node("N2", "Y1")),
...                   outlets=(Node("N3", "X"), Node("N4", "Y2")),
...                   receivers=(Node("N5", "X"), Node("N6", "Y3")),
...                   senders=(Node("N7", "X"), Node("N8", "Y4")))

Property variables puts all the different variables of these nodes together:

>>> sorted(element.variables)
['X', 'Y1', 'Y2', 'Y3', 'Y4']

open_files(idx: int = 0) → None

Call method open_files() of the Sequences object handled (indirectly) by the actual Element object.

close_files() → None

Call method close_files() of the Sequences object handled (indirectly) by the actual Element object.

prepare_allseries(ramflag: bool = True) → None

Prepare the series objects of all input, flux and state sequences of the model handled by this element.

Call this method before a simulation run, if you need access to (nearly) all simulated series of the handled model after the simulation run is finished.

By default, the time-series are stored in RAM, which is the faster option. If your RAM is limited, pass False to function argument ramflag to store the series on disk.

prepare_inputseries(ramflag: bool = True) → None

Prepare the series objects of the input sequences of the model handled by this element.

See method prepare_allseries() for further information.

prepare_fluxseries(ramflag: bool = True) → None

Prepare the series objects of the flux sequences of the model handled by this element.

See method prepare_allseries() for further information.

prepare_stateseries(ramflag: bool = True) → None

Prepare the series objects of the state sequences of the model handled by this element.

See method prepare_allseries() for further information.

plot_inputseries(names: Optional[Sequence[str]] = None, *, average: bool = False, labels: Optional[Tuple[str, ...]] = None, colors: Optional[Union[str, Tuple[str, ...]]] = None, linestyles: Optional[Union[typing_extensions.Literal[-, --, -., :, solid, dashed, dashdot, dotted], Tuple[typing_extensions.Literal[-, --, -., :, solid, dashed, dashdot, dotted], ...]]] = None, linewidths: Optional[Union[int, Tuple[int, ...]]] = None, focus: bool = True) → matplotlib.figure.Figure

Plot (the selected) InputSequence series values.

We demonstrate the functionalities of method plot_inputseries() based on the Lahn example project:

>>> from hydpy.examples import prepare_full_example_2
>>> hp, pub, _ = prepare_full_example_2(lastdate="1997-01-01")

Without any arguments, plot_inputseries() prints the time-series of all input sequences handled by its Model object directly to the screen (in our example P, T, TN, and EPN of application model hland_v1):

>>> land = hp.elements.land_dill
>>> figure = land.plot_inputseries()

You can use the pyplot API of matplotlib to modify the returned figure or to save it to disk (or print it to the screen, in case the interactive mode of matplotlib is disabled):

>>> from hydpy.core.testtools import save_autofig
>>> save_autofig("Element_plot_inputseries.png", figure)

Methods plot_fluxseries() and plot_stateseries() work in the same manner. Before applying them, one has to calculate the time-series of the FluxSequence and StateSequence objects first:

>>> hp.simulate()

All three methods allow selecting specific sequences by passing their names (here, flux sequences Q0 and Q1 of hland_v1). Additionally, you can pass general or individual values to the arguments labels, colors, linestyles, and linewidths:

>>> figure = land.plot_fluxseries(
...     ["q0", "q1"], labels=("direct runoff", "base flow"),
...     colors=("red", "green"), linestyles="--", linewidths=2)
>>> save_autofig("Element_plot_fluxseries.png", figure)

For 1-dimensional IOSequence objects, all three methods plot the individual time-series in the same colour. We demonstrate this for the frozen (SP) and the liquid (WC) water equivalent of the snow cover of different hydrological response units. Therefore, we restrict the shown period to February and March via the eval_ time-grid:

>>> with pub.timegrids.eval_(firstdate="1996-02-01", lastdate="1996-04-01"):
...     figure = land.plot_stateseries(["sp", "wc"])
>>> save_autofig("Element_plot_stateseries1.png", figure)

Alternatively, you can print the averaged time-series by assigning True to argument average. We demonstrate this functionality for the state sequence SM (this time, without focusing on the time-series y-extent:

>>> figure = land.plot_stateseries(["sm"], colors=("grey",))
>>> figure = land.plot_stateseries(
...     ["sm"], average=True, focus=False, colors="black", linewidths=3)
>>> save_autofig("Element_plot_stateseries2.png", figure)

plot_fluxseries(names: Optional[Sequence[str]] = None, *, average: bool = False, labels: Optional[Tuple[str, ...]] = None, colors: Optional[Union[str, Tuple[str, ...]]] = None, linestyles: Optional[Union[typing_extensions.Literal[-, --, -., :, solid, dashed, dashdot, dotted], Tuple[typing_extensions.Literal[-, --, -., :, solid, dashed, dashdot, dotted], ...]]] = None, linewidths: Optional[Union[int, Tuple[int, ...]]] = None, focus: bool = True) → matplotlib.figure.Figure

Plot the flux series of the handled model.

See the documentation on method plot_inputseries() for additional information.

plot_stateseries(names: Optional[Sequence[str]] = None, *, average: bool = False, labels: Optional[Tuple[str, ...]] = None, colors: Optional[Union[str, Tuple[str, ...]]] = None, linestyles: Optional[Union[typing_extensions.Literal[-, --, -., :, solid, dashed, dashdot, dotted], Tuple[typing_extensions.Literal[-, --, -., :, solid, dashed, dashdot, dotted], ...]]] = None, linewidths: Optional[Union[int, Tuple[int, ...]]] = None, focus: bool = True) → matplotlib.figure.Figure

Plot the state series of the handled model.

See the documentation on method plot_inputseries() for additional information.

assignrepr(prefix: str) → str

Return a repr() string with a prefixed assignment.

hydpy.core.devicetools.clear_registries_temporarily()

Context manager for clearing the current Node, Element, and FusedVariable registries .

Function clear_registries_temporarily() is only available for testing purposes.

These are the relevant registries for the currently initialised Node, Element, and FusedVariable objects:

>>> from hydpy.core import devicetools
>>> registries = (devicetools._id2devices,
...               devicetools._registry[devicetools.Node],
...               devicetools._registry[devicetools.Element],
...               devicetools._selection[devicetools.Node],
...               devicetools._selection[devicetools.Element],
...               devicetools._registry_fusedvariable)

We first clear them and, just for testing, insert some numbers:

>>> for idx, registry in enumerate(registries):
...     registry.clear()
...     registry[idx] = idx+1

Within the with block, all registries are empty:

>>> with devicetools.clear_registries_temporarily():
...     for registry in registries:
...         print(registry)
{}
{}
{}
{}
{}
{}

Before leaving the with block, the clear_registries_temporarily() method restores the contents of each dictionary:

>>> for registry in registries:
...     print(registry)
...     registry.clear()
{0: 1}
{1: 2}
{2: 3}
{3: 4}
{4: 5}
{5: 6}