Allow signal names to be used for time/freq responses and subsystem indexing #1069

murrayrm · 2024-12-01T20:47:22Z

This PR adds the ability to access response signals and subsystem inputs and outputs using signal names. As described in the documentation:

Time signal indexing:

The input, output, and state elements of the response can be access using signal names in place of integer offsets::
plt.plot(response. time, response.states['x[1]']
For multi-trace systems generated by :func:step_response and :func:impulse_response, the input name used to generate the trace can be used to access the appropriate input output pair::
plt.plot(response.time, response.outputs['y[0]', 'u[1]'])

Frequency response indexing:

Frequency response objects are also available as named properties of the response object: response.magnitude, response.phase, and response.response (for the complex response). For MIMO systems, these elements of the frequency response can be accessed using the names of the inputs and outputs::
response.magnitude['y[0]', 'u[1]']
where the signal names are based on the system that generated the frequency response.

Subsystem indexing:

Subsets of input/output pairs for LTI systems can be obtained by indexing the system using either numerical indices (including slices) or signal names::
subsys = sys[[0, 2], 0:2]
subsys = sys[['y[0]', 'y[2]'], ['u[0]', 'u[1]']]
Signal names for an indexed subsystem are preserved from the original system and the subsystem name is set according to the values of control.config.defaults['iosys.indexed_system_name_prefix'] and control.config.defaults['iosys.indexed_system_name_suffix']`. The default subsystem name is the original system name with '$indexed' appended.

Summary of changes:

Signals are now returned as a NamedSignal object, which is a subclass of np.ndarray that overrides the __getitem__ method to allow processing of signal names via the _parse_key method.
All signal/subsystem indexing now allows integers, strings (new), lists of integers or strings (new), or slices.
Refactored code for processing signal names to make everything consistent across time and frequency domain signals as well as state and input/output vectors. See iosys.NamedSignal._parse_key and changes in frdata.py and timeresp.py.
Refactored code for processing subsystem indices and made index processing consistent for StateSpace, TransferFunction, and FrequencyResponseData systems. See iosys._process_subsys_index and changes in frdata.py, statesp.py, and xferfcn.py.
Unit tests, docstrings, and user documentation updated to cover new functiionality.

…ycot

coveralls · 2024-12-01T21:03:11Z

coverage: 94.721% (+0.02%) from 94.697%
when pulling 7ef09a0 on murrayrm:named_signals-29Nov2024
into 57b5307 on python-control:main.

slivingston

Almost done with review; it will be done tomorrow. For now, I am sending minor style comments.

slivingston · 2024-12-01T22:40:22Z

control/iosys.py

+
+    def __array_finalize__(self, obj):
+        # See https://numpy.org/doc/stable/user/basics.subclassing.html
+        if obj is None: return


Suggested change

if obj is None: return

if obj is None:

return

return should go on the next line to make it more obvious what is in the if-block. Also, this is consistent with PEP 8:

Compound statements (multiple statements on the same line) are generally discouraged

The example in the NumPy docs has obj is None: return (on 1 line), but my style comment remains. I do not know why the example there has this 1-line style, but I suspect it is to keep examples short, which would also justify there being only 1 blank line after import in those examples.

slivingston · 2024-12-02T01:25:02Z

control/iosys.py

+        idx = idx[0]
+
+    # Convert int to slice so that numpy doesn't drop dimension
+    if isinstance(idx, int): idx = slice(idx, idx+1, 1)


Suggested change

if isinstance(idx, int): idx = slice(idx, idx+1, 1)

if isinstance(idx, int):

idx = slice(idx, idx+1, 1)

Similar to my other comment, statements should be on separate lines for clarity of style (as per PEP 8).

slivingston · 2024-12-02T01:25:55Z

control/iosys.py

+#
+def _process_subsys_index(idx, sys_labels, slice_to_list=False):
+    if not isinstance(idx, (slice, list, int)):
+        raise TypeError(f"system indices must be integers, slices, or lists")


This string does not need the f prefix, but OK to keep it if you anticipate expressions being added to it later.

slivingston · 2024-12-02T01:30:26Z

control/tests/lti_test.py

+    sys = ct.rss(4, 3, 3)
+    subsys = sys[key]
+
+    # Construct the system to be test


Suggested change

# Construct the system to be test

# Construct the system to be tested

slivingston · 2024-12-02T02:10:18Z

control/timeresp.py


         response(tranpose=True).input

-       See :meth:`TimeResponseData.__call__` for more information.
+     See :meth:`TimeResponseData.__call__` for more information.


Suggested change

See :meth:`TimeResponseData.__call__` for more information.

See :meth:`TimeResponseData.__call__` for more information.

slivingston · 2024-12-02T21:34:30Z

doc/conventions.rst

@@ -242,6 +271,17 @@ such as the :func:`step_response` function applied to a MIMO system,
 which will compute the step response for each input/output pair.  See
 :class:`TimeResponseData` for more details.

+The input, output, and state elements of the response can be access using


Suggested change

The input, output, and state elements of the response can be access using

The input, output, and state elements of the response can be accessed using

slivingston · 2024-12-02T21:58:34Z

doc/plotting.rst

+Access to frequency response data is available via the attributes
+``omega``, ``magnitude``,` `phase``, and ``response``, where ``response``
+represents the complex value of the frequency response at each frequency.
+The ``magnitude``,` `phase``, and ``response`` arrays can be indexed using


Suggested change

The ``magnitude``,` `phase``, and ``response`` arrays can be indexed using

The ``magnitude``, ``phase``, and ``response`` arrays can be indexed using

slivingston · 2024-12-03T03:21:40Z

doc/conventions.rst

+`control.config.defaults['iosys.indexed_system_name_prefix']` and
+`control.config.defaults['iosys.indexed_system_name_suffix']`.  The default


Suggested change

`control.config.defaults['iosys.indexed_system_name_prefix']` and

`control.config.defaults['iosys.indexed_system_name_suffix']`. The default

``control.config.defaults['iosys.indexed_system_name_prefix']`` and

``control.config.defaults['iosys.indexed_system_name_suffix']``. The default

rst files built with Sphinx require double backtick (``) to render as in-line code.

slivingston · 2024-12-03T03:23:13Z

doc/conventions.rst

+Note: The `fresp` data member is stored as a NumPy array and cannot be
+accessed with signal names.  Use `response.response` to access the complex


Suggested change

Note: The `fresp` data member is stored as a NumPy array and cannot be

accessed with signal names. Use `response.response` to access the complex

Note: The ``fresp`` data member is stored as a NumPy array and cannot be

accessed with signal names. Use ``response.response`` to access the complex

slivingston · 2024-12-03T03:23:54Z

doc/conventions.rst

+`response` object: `response.magnitude`, `response.phase`, and
+`response.response` (for the complex response).  For MIMO systems, these


Suggested change

`response` object: `response.magnitude`, `response.phase`, and

`response.response` (for the complex response). For MIMO systems, these

``response`` object: ``response.magnitude``, ``response.phase``, and

``response.response`` (for the complex response). For MIMO systems, these

murrayrm added 11 commits November 30, 2024 08:53

clean up _process_time_response

5d7fb42

implement NamedSignal's for time responses

5df6fb7

implement NamedSignal's for frequency responses

b382abf

add string-based indexing of state space systems

58922ce

add string-based indexing of transfer functions

e52fca6

add string-based indexing of FRD systems

cca4d13

fix NamedSignal.__getitem__ for new versions of NumPy + unit tests/sl…

944b6a2

…ycot

update index checking + docstrings

cd3d315

add documentation for indexing by name + update docstrings

df33002

use common processing for state response

1903055

TRV: typo in documentation

fba414d

slivingston self-requested a review December 1, 2024 22:26

slivingston reviewed Dec 3, 2024

View reviewed changes

address initial @slivingston comments

7ef09a0

slivingston approved these changes Dec 4, 2024

View reviewed changes

murrayrm merged commit 12dda4e into python-control:main Dec 4, 2024
23 checks passed

murrayrm added this to the 0.10.2 milestone Feb 19, 2025

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	if isinstance(idx, int): idx = slice(idx, idx+1, 1)
	if isinstance(idx, int):
	idx = slice(idx, idx+1, 1)

	# Construct the system to be test
	# Construct the system to be tested

	See :meth:`TimeResponseData.__call__` for more information.
	See :meth:`TimeResponseData.__call__` for more information.

	The input, output, and state elements of the response can be access using
	The input, output, and state elements of the response can be accessed using

	The ``magnitude``,` `phase``, and ``response`` arrays can be indexed using
	The ``magnitude``, ``phase``, and ``response`` arrays can be indexed using

		`control.config.defaults['iosys.indexed_system_name_prefix']` and
		`control.config.defaults['iosys.indexed_system_name_suffix']`. The default

		Note: The `fresp` data member is stored as a NumPy array and cannot be
		accessed with signal names. Use `response.response` to access the complex

		`response` object: `response.magnitude`, `response.phase`, and
		`response.response` (for the complex response). For MIMO systems, these

Allow signal names to be used for time/freq responses and subsystem indexing #1069

Allow signal names to be used for time/freq responses and subsystem indexing #1069

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