8000 Fix few docstring things, change name to eigensys_realization · python-control/python-control@4ea1d82 · GitHub
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Fix few docstring things, change name to eigensys_realization
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‎control/modelsimp.py

Lines changed: 28 additions & 29 deletions
Original file line numberDiff line numberDiff line change
@@ -50,7 +50,7 @@
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from .statefbk import gram
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from .timeresp import TimeResponseData
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53-
__all__ = ['hsvd', 'balred', 'modred', 'era', 'markov', 'minreal']
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__all__ = ['hsvd', 'balred', 'modred', 'eigensys_realization', 'markov', 'minreal','era']
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# Hankel Singular Value Decomposition
@@ -369,10 +369,11 @@ def minreal(sys, tol=None, verbose=True):
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return sysr
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372-
def era(arg, r, m=None, n=None, dt=True, transpose=False):
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r"""era(YY, r)
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def eigensys_realization(arg, r, m=None, n=None, dt=True, transpose=False):
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r"""eigensys_realization(YY, r)
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375-
Calculate an ERA model of order `r` based on the impulse-response data.
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Calculate an ERA model of order `r` based on the impulse-response data
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`YY`.
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This function computes a discrete time system
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@@ -385,73 +386,68 @@ def era(arg, r, m=None, n=None, dt=True, transpose=False):
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The function can be called with 2 arguments:
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388-
* ``sysd, S = era(data, r)``
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* ``sysd, S = era(YY, r)``
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* ``sysd, S = eigensys_realization(data, r)``
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* ``sysd, S = eigensys_realization(YY, r)``
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where `response` is an `TimeResponseData` object, and `YY` is 1D or 3D
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array and r is an integer.
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Parameters
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----------
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YY : array_like
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impulse-response data from which the StateSpace model is estimated,
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1D or 3D array.
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Impulse response from which the StateSpace model is estimated, 1D
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or 3D array.
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data : TimeResponseData
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impulse-response data from which the StateSpace model is estimated.
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Impulse response from which the StateSpace model is estimated.
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r : integer
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Order of model.
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m : integer, optional
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Number of rows in Hankel matrix.
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Default is 2*r.
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Number of rows in Hankel matrix. Default is 2*r.
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n : integer, optional
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Number of columns in Hankel matrix.
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Default is 2*r.
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Number of columns in Hankel matrix. Default is 2*r.
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dt : True or float, optional
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True indicates discrete time with unspecified sampling time,
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positive number is discrete time with specified sampling time.
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It can be used to scale the StateSpace model in order to match
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the impulse response of this library.
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Default values is True.
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positive number is discrete time with specified sampling time. It
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can be used to scale the StateSpace model in order to match the
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impulse response of this library. Default is True.
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transpose : bool, optional
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Assume that input data is transposed relative to the standard
417-
:ref:`time-series-convention`. For TimeResponseData this parameter
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is ignored.
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Default value is False.
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:ref:`time-series-convention`. For TimeResponseData this parameter
416+
is ignored. Default is False.
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Returns
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-------
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sys : StateSpace
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A reduced order model sys=StateSpace(Ar,Br,Cr,Dr,dt).
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S : array
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Singular values of Hankel matrix.
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Can be used to choose a good r value.
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Singular values of Hankel matrix. Can be used to choose a good r
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value.
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References
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----------
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.. [1] Samet Oymak and Necmiye Ozay
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Non-asymptotic Identification of LTI Systems
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from a Single Trajectory.
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.. [1] Samet Oymak and Necmiye Ozay, Non-asymptotic Identification of
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LTI Systems from a Single Trajectory.
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https://arxiv.org/abs/1806.05722
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Examples
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--------
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>>> T = np.linspace(0, 10, 100)
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>>> _, YY = ct.impulse_response(ct.tf([1], [1, 0.5], True), T)
440-
>>> sysd, _ = ct.era(YY, r=1)
436+
>>> sysd, _ = ct.eigensys_realization(YY, r=1)
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>>> T = np.linspace(0, 10, 100)
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>>> response = ct.impulse_response(ct.tf([1], [1, 0.5], True), T)
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>>> sysd, _ = ct.era(response, r=1)
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>>> sysd, _ = ct.eigensys_realization(response, r=1)
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"""
446442
def block_hankel_matrix(Y, m, n):
447-
443+
"""Create a block hankel matrix from Impulse response"""
448444
q, p, _ = Y.shape
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YY = Y.transpose(0,2,1) # transpose for reshape
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451447
H = np.zeros((q*m,p*n))
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453449
for r in range(m):
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# shift and add row to hankel matrix
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# shift and add row to Hankel matrix
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new_row = YY[:,r:r+n,:]
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H[q*r:q*(r+1),:] = new_row.reshape((q,p*n))
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@@ -651,3 +647,6 @@ def markov(Y, U, m=None, transpose=False):
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652648
# Return the first m Markov parameters
653649
return H if transpose else np.transpose(H)
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# Function aliases
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era = eigensys_realization

‎control/tests/modelsimp_test.py

Lines changed: 5 additions & 5 deletions
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@@ -10,7 +10,7 @@
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from control import StateSpace, impulse_response, step_response, forced_response, tf, rss, c2d
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from control.exception import ControlMIMONotImplemented
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from control.tests.conftest import slycotonly
13-
from control.modelsimp import balred, hsvd, markov, modred, era
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from control.modelsimp import balred, hsvd, markov, modred, eigensys_realization
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class TestModelsimp:
@@ -129,15 +129,15 @@ def testERASignature(self):
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ir_true = impulse_response(sysd_true,T=T)
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131131
# test TimeResponseData
132-
sysd_est, _ = era(ir_true,r=2)
132+
sysd_est, _ = eigensys_realization(ir_true,r=2)
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ir_est = impulse_response(sysd_est, T=T)
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_, H_est = ir_est
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136136
np.testing.assert_allclose(H_true, H_est, rtol=1e-6, atol=1e-8)
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138138
# test ndarray
139139
_, YY_true = ir_true
140-
sysd_est, _ = era(YY_true,r=2)
140+
sysd_est, _ = eigensys_realization(YY_true,r=2)
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ir_est = impulse_response(sysd_est, T=T)
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_, H_est = ir_est
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@@ -169,7 +169,7 @@ def testERASignature(self):
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ir_true = impulse_response(sysd_true, T=T)
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171171
# test TimeResponseData
172-
sysd_est, _ = era(ir_true,r=4,dt=dt)
172+
sysd_est, _ = eigensys_realization(ir_true,r=4,dt=dt)
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174174
step_true = step_response(sysd_true)
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step_est = step_response(sysd_est)
@@ -180,7 +180,7 @@ def testERASignature(self):
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181181
# test ndarray
182182
_, YY_true = ir_true
183-
sysd_est, _ = era(YY_true,r=4,dt=dt)
183+
sysd_est, _ = eigensys_realization(YY_true,r=4,dt=dt)
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185185
step_true = step_response(sysd_true, T=T)
186186
step_est = step_response(sysd_est, T=T)

‎doc/control.rst

Lines changed: 1 addition & 1 deletion
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@@ -137,7 +137,7 @@ Model simplification tools
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balred
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hsvd
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modred
140-
era
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eigensys_realization
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markov
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Nonlinear system support

‎doc/timeplot-mimo_ioresp-mt_tr.png

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‎doc/timeplot-mimo_ioresp-ov_lm.png

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‎doc/timeplot-mimo_step-default.png

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‎doc/timeplot-mimo_step-linestyle.png

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‎doc/timeplot-mimo_step-pi_cs.png

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‎examples/era_msd.py

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@@ -47,7 +47,7 @@
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response.plot()
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plt.show()
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50-
sysd_est, _ = ct.era(response,r=4,dt=dt)
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sysd_est, _ = ct.eigensys_realization(response,r=4,dt=dt)
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step_true = ct.step_response(sysd)
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step_true.sysname="H_true"

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