Bases: object

Base class for input/output systems.

The InputOutputSystem class allows (possibly nonlinear) input/output systems to be represented in Python. It is used as a parent class for a set of subclasses that are used to implement specific structures and operations for different types of input/output dynamical systems.

The timebase for the system, dt, is used to specify whether the system is operating in continuous or discrete time. It can have the following values:

• dt = None: No timebase specified

• dt = 0: Continuous time system

• dt > 0: Discrete time system with sampling time dt

• dt = True: Discrete time system with unspecified sampling time

Parameters:

inputsint, list of str, or None

Description of the system inputs. This can be given as an integer count or a list of strings that name the individual signals. If an integer count is specified, the names of the signal will be of the form ‘s[i]’ (where ‘s’ is given by the input_prefix parameter and has default value ‘u’). If this parameter is not given or given as None, the relevant quantity will be determined when possible based on other information provided to functions using the system.

outputsint, list of str, or None

Description of the system outputs. Same format as inputs, with the prefix given by output_prefix (defaults to ‘y’).

statesint, list of str, or None

Description of the system states. Same format as inputs, with the prefix given by state_prefix (defaults to ‘x’).

dtNone, True or float, optional

System timebase. 0 (default) indicates continuous time, True indicates discrete time with unspecified sampling time, positive number is discrete time with specified sampling time, None indicates unspecified timebase (either continuous or discrete time).

namestring, optional

System name (used for specifying signals). If unspecified, a generic name ‘sys[id]’ is generated with a unique integer id.

paramsdict, optional

Parameter values for the system. Passed to the evaluation functions for the system as default values, overriding internal defaults.

Attributes:

ninputs, noutputs, nstatesint

Number of input, output, and state variables.

input_index, output_index, state_indexdict

Dictionary of signal names for the inputs, outputs, and states and the index of the corresponding array.

input_labels, output_labels, state_labelslist of str

List of signal names for inputs, outputs, and states.

shapetuple

2-tuple of I/O system dimension, (noutputs, ninputs).

Other Parameters:

input_prefixstring, optional

Set the prefix for input signals. Default = ‘u’.

output_prefixstring, optional

Set the prefix for output signals. Default = ‘y’.

state_prefixstring, optional

Set the prefix for state signals. Default = ‘x’.

repr_formatstr

String representation format. See control.iosys_repr.

Attributes

Methods

copy(name=None, use_prefix_suffix=True)[source]

Make a copy of an input/output system.

A copy of the system is made, with a new name. The name keyword can be used to specify a specific name for the system. If no name is given and use_prefix_suffix is True, the name is constructed by prepending config.defaults['iosys.duplicate_system_name_prefix'] and appending config.defaults['iosys.duplicate_system_name_suffix']. Otherwise, a generic system name of the form ‘sys[<id>]’ is used, where ‘<id>’ is based on an internal counter.

Parameters:

namestr, optional

Name of the newly created system.

use_prefix_suffixbool, optional

If True and name is None, set the name of the new system to the name of the original system with prefix config.defaults['duplicate_system_name_prefix'] and suffix config.defaults['duplicate_system_name_suffix'].

Returns:

InputOutputSystem

dt

System timebase.

find_input(name)[source]

Find the index for an input given its name (None if not found).

Parameters:

namestr

Signal name for the desired input.

Returns:

int

Index of the named input.

find_inputs(name_list)[source]

Return list of indices matching input spec (None if not found).

Parameters:

name_liststr or list of str

List of signal specifications for the desired inputs. A signal can be described by its name or by a slice-like description of the form ‘start:end` where ‘start’ and ‘end’ are signal names. If either is omitted, it is taken as the first or last signal, respectively.

Returns:

list of int

List of indices for the specified inputs.

find_output(name)[source]

Find the index for a output given its name (None if not found).

Parameters:

namestr

Signal name for the desired output.

Returns:

int

Index of the named output.

find_outputs(name_list)[source]

Return list of indices matching output spec (None if not found).

Parameters:

name_liststr or list of str

List of signal specifications for the desired outputs. A signal can be described by its name or by a slice-like description of the form ‘start:end` where ‘start’ and ‘end’ are signal names. If either is omitted, it is taken as the first or last signal, respectively.

Returns:

list of int

List of indices for the specified outputs.

find_state(name)[source]

Find the index for a state given its name (None if not found).

Parameters:

namestr

Signal name for the desired state.

Returns:

int

Index of the named state.

find_states(name_list)[source]

Return list of indices matching state spec (None if not found).

Parameters:

name_liststr or list of str

List of signal specifications for the desired states. A signal can be described by its name or by a slice-like description of the form ‘start:end` where ‘start’ and ‘end’ are signal names. If either is omitted, it is taken as the first or last signal, respectively.

Returns:

list of int

List of indices for the specified states..

property input_labels

List of labels for the input signals.

isctime(strict=False)[source]

Check to see if a system is a continuous-time system.

Parameters:

strictbool, optional

If strict is True, make sure that timebase is not None. Default is False.

isdtime(strict=False)[source]

Check to see if a system is a discrete-time system.

Parameters:

strictbool, optional

If strict is True, make sure that timebase is not None. Default is False.

issiso()[source]

Check to see if a system is single input, single output.

ninputs

Number of system inputs.

noutputs

Number of system outputs.

nstates

Number of system states.

property output_labels

List of labels for the output signals.

property repr_format

String representation format.

Format used in creating the representation for the system:

• ‘info’ : <IOSystemType sysname: [inputs] -> [outputs]>

• ‘eval’ : system specific, loadable representation

• ‘latex’ : HTML/LaTeX representation of the object

The default representation for an input/output is set to ‘eval’. This value can be changed for an individual system by setting the repr_format parameter when the system is created or by setting the repr_format property after system creation. Set config.defaults['iosys.repr_format'] to change for all I/O systems or use the repr_format parameter/attribute for a single system.

set_inputs(inputs, prefix='u')[source]

Set the number/names of the system inputs.

Parameters:

inputsint, list of str, or None

Description of the system inputs. This can be given as an integer count or as a list of strings that name the individual signals. If an integer count is specified, the names of the signal will be of the form ‘u[i]’ (where the prefix ‘u’ can be changed using the optional prefix parameter).

prefixstring, optional

If inputs is an integer, create the names of the states using the given prefix (default = ‘u’). The names of the input will be of the form ‘prefix[i]’.

set_outputs(outputs, prefix='y')[source]

Set the number/names of the system outputs.

Parameters:

outputsint, list of str, or None

Description of the system outputs. This can be given as an integer count or as a list of strings that name the individual signals. If an integer count is specified, the names of the signal will be of the form ‘y[i]’ (where the prefix ‘y’ can be changed using the optional prefix parameter).

prefixstring, optional

If outputs is an integer, create the names of the states using the given prefix (default = ‘y’). The names of the input will be of the form ‘prefix[i]’.

set_states(states, prefix='x')[source]

Set the number/names of the system states.

Parameters:

statesint, list of str, or None

Description of the system states. This can be given as an integer count or as a list of strings that name the individual signals. If an integer count is specified, the names of the signal will be of the form ‘x[i]’ (where the prefix ‘x’ can be changed using the optional prefix parameter).

prefixstring, optional

If states is an integer, create the names of the states using the given prefix (default = ‘x’). The names of the input will be of the form ‘prefix[i]’.

property shape

2-tuple of I/O system dimension, (noutputs, ninputs).

property state_labels

List of labels for the state signals.

update_names([name, inputs, outputs, states])[source]

Update signal and system names for an I/O system.

Parameters:

namestr, optional

New system name.

inputslist of str, int, or None, optional

List of strings that name the individual input signals. If given as an integer or None, signal names default to the form ‘u[i]’. See InputOutputSystem for more information.

outputslist of str, int, or None, optional

Description of output signals; defaults to ‘y[i]’.

statesint, list of str, int, or None, optional

Description of system states; defaults to ‘x[i]’.

input_prefixstring, optional

Set the prefix for input signals. Default = ‘u’.

output_prefixstring, optional

Set the prefix for output signals. Default = ‘y’.

state_prefixstring, optional

Set the prefix for state signals. Default = ‘x’.