Sisotool and dynamic root locus zoom #209

icam0 · 2018-06-03T17:58:07Z

This pull request introduces two new features to the python-control package. A matlab inspired sisotool and dynamic recomputing of the root locus plot when zooming.

Sisotool
In the pictures below a comparison can be seen between the matlab sisotool, the sisotool for matlplotlib 1.x.x and matlplotlib 2.x.x respectively.

matlab

matplotlib 1.x.x

matplotlib 2.x.x

The function is essentially a wrapper around the rootlocus, bode and step response functions. When a click is made on the rootlocus plot, the purple point(s) are moved and the other plots are updated as well. Note that a decision was made to keep most of the rootlocus plot update logic inside the rootlocus file and the logic behind updating the other 2 plots in _sisotoolupdate in sisotool.py. Also, use was made of **kwargs whenever neccessary in order to not confuse the end user with parameters in functions without documenting them. Also, this was tested on python 2.7, 3.3 and 3.6 and matplotlib 1.5.3 and 2.2.2 on mac os x. It would be greatly appreciated if more testers can try this on their machine.

**Dynamic zooming of the root locus plot **
Firstly, I want to point out an error in existing code in the following code snippet from _default_gains:

    while (indexes_too_far[0].size > 0) and (kvect.size < 5000):
        for index in indexes_too_far[0]:
            new_gains = np.linspace(kvect[index], kvect[index+1], 5)
            new_points = _RLFindRoots(num, den, new_gains[1:4])
            kvect = np.insert(kvect, index+1, new_gains[1:4])
            mymat = np.insert(mymat, index+1, new_points, axis=0)

Every iteration, 3 points are inserted at the index where the distance between 2 points is too large. What goes wrong however, is that the indexes are not updated. So when for example indexes_too_far = [0,1,2] and in the first iteration 3 points in between 0 and 1 are inserted. The next iteration the points will be inserted in between 1 and 2. However, this point has shifted its index with 3. This is fixed by the following:

    while (len(indexes_too_far) > 0) and (kvect.size < 5000):
        for counter,index in enumerate(indexes_too_far):
            index = index + counter*3
            new_gains = np.linspace(kvect[index], kvect[index + 1], 5)
            new_points = _RLFindRoots(num, den, new_gains[1:4])
            kvect = np.insert(kvect, index + 1, new_gains[1:4])
            mymat = np.insert(mymat, index + 1, new_points, axis=0)

Now a new function _indexes_filt is added which also takes into account if the user is zoomed in on a part of the plot and adds more points to indexes_too_far. If no initial points are within the zoom view, it detects at which point one of the points crosses an xlim or ylim of the zoombox and then more points are added until the zoom tolerance requirements are met.

This pull request also includes the #199 and #204 pull requests, because they are an integral part of the sisotool as well. Please note that the Travis CI build sometimes fails due to issue #194 . I was able to get the build passing (https://travis-ci.org/icam0/python-control/builds/387446241) by restarting 2 subbuilds once.

i Please enter a commit message to explain why this merge is necessaryskldfj,

…phase limit bug.

…g issue.

…as present

coveralls · 2018-06-03T18:10:36Z

Coverage increased (+1.0%) to 78.881% when pulling 70ec8be on icam0:sisotool_final into 601b581 on python-control:master.

coveralls · 2018-06-03T18:10:36Z

Coverage increased (+1.0%) to 78.881% when pulling 70ec8be on icam0:sisotool_final into 601b581 on python-control:master.

coveralls · 2018-06-03T18:10:36Z

Coverage decreased (-0.05%) to 78.222% when pulling 17c4a95 on icam0:sisotool_final into 1254ccb on python-control:master.

coveralls · 2018-06-03T18:10:36Z

Coverage increased (+1.0%) to 78.881% when pulling 70ec8be on icam0:sisotool_final into 601b581 on python-control:master.

repagh · 2018-06-24T12:10:03Z

I tested locally, and this works fine!

murrayrm

Some small comments on docstrings.

murrayrm · 2018-07-14T01:56:06Z

control/timeresp.py

@@ -339,7 +339,7 @@ def forced_response(sys, T=None, U=0., X0=0., transpose=False):
 def _get_ss_simo(sys, input=None, output=None):
    """Return a SISO or SIMO state-space version of sys

-    If input is not specified, select first input and issue warning
+    If input is not sfpecified, select first input and issue warning


Please remove this change, which inserts a misspelling.

murrayrm · 2018-07-14T01:57:04Z

control/sisotool.py

+
+def sisotool(sys, kvect = None, xlim_rlocus = None, ylim_rlocus = None, plotstr_rlocus = 'b' if int(matplotlib.__version__[0]) == 1 else 'C0',rlocus_grid = False, omega = None, dB = None, Hz = None, deg = None, omega_limits = None, omega_num = None,margins_bode = True, tvect=None):
+
+    """Sisotool


Documentation style is a bit nonstandard. I think the Sisotool on its own line can be removed. This will look odd on readthedocs since the function name will already be listed.

murrayrm · 2018-07-14T01:57:30Z

control/sisotool.py

+
+    """Sisotool
+
+    Sisotool style collection of plots inspired by the matlab sisotool.


MATLAB should be in all caps.

murrayrm · 2018-07-14T02:02:12Z

Very nice tool. I tried it out on Python 3.5 on MacOS 10.13 (High Sierra) and it worked well.

If someone can test this on Linux (and Windows?) and confirm that it works, we can incorporate into the next release.

murrayrm · 2018-12-31T18:03:42Z

I tried out the tool and it works most of the time. But there can be problems if changing the gain if the scale of the plot is too large. For example, try the following example:

import control
sys = control.tf([10,100], [1,5,9,5])
control.sisotool(sys)

This will generate a matplotlib window and you can click on the root locus branches on the right hand side to change the gain. But if you try to click on the left branch (on the negative real axis), it doesn't get recognized.

I think the problem is that the scaling parameters that are used to determine if you are close enough to the axis don't work for the scaling on this plot.

@icam0 If there is no easy fix, we can merge this change as is and update later. I'll wait for a few days to get your input.

icam0 · 2019-01-03T06:53:18Z

I suspect the gain tolerance to be too small for some reason (lines 455 and 457 of the rlocus.py file). I will get back to you during the weekend when I take a closer look at this.

icam0 · 2019-01-13T12:19:46Z

I have looked into it, what happens is that because this plot generates a very skewed aspect ratio due to the automatic matplotlib scaling of the plot the left side of the plot 'does not seem to work'. This is due to the fact that I made a decision to vary the gain tolerance according to the zoom and xlimit and ylimit of the plot. It selects the smallest of these 2 and bases the gain tolerance on the smallest of these 2 margins. When having a skewed aspect ratio it makes it hard for the user to click because the margin becomes very small. In the original implementation, there was a 'fixed' 0.04 factor in there which meant that if you would zoom in a lot, you could click very far away from the plot resulting in floating dots far away from the plot line. Using a scaled gain factor fixed this problem.

If you were to just increase the gain tolerance the behaviour becomes more unreliable and the point sometimes snaps to the incorrect line from then a user would intend. Therefore, for now, I'd like to propose to scale axes of the root locus plot to the same length of the smallest axis. Which makes sure the initial plot is always clickable. Something like this would then be added to the end of the rlocus.py plot (an edge case for handling when the user specifies the xlim or ylim would still need to be added):

x0, x1 = ax.get_xlim()
y0, y1 = ax.get_ylim()
if abs(x0-x1) >= abs(y0-y1):
    ax.set_xlim(0. - 0.5*abs(y0-y1) ,0. +0.5*abs(y0-y1))
else:
    ax.set_ylim(0. - 0.5 * abs(x0 - x1), 0. + 0.5 * abs(x0 - x1))

However, when the user zooms in with a very skewed aspect ratio clicking the line would still be very difficult which is why I think in the future a more sophisticated algorithm for click detection would be a worthwhile enhancement. I'd like to get your thoughts on this @murrayrm

murrayrm · 2019-04-07T01:53:43Z

@icam0 Can you rebase this against the current master and resolve the conflicts. I think this is ready to go into release 0.8.2 as soon as that is done.

murrayrm · 2019-04-11T20:52:31Z

Did an inline correction of the conflicts. Will merge if tests run correctly.

murrayrm · 2019-04-12T05:35:25Z

Fixed up remaining issues. Ready to merge.

icam0 added 20 commits May 23, 2018 15:02

first sisotool chechpoint

54583d5

second sisotool checkpoint

2e1bf7d

changed matplotlib event handler

f4545dd

improved sisotool readability

e3c1f31

Merge branch 'bode_margins_plot' into sisotool_merge

72ffb63

i Please enter a commit message to explain why this merge is necessaryskldfj,

Added display of GM and PM in bode plot. Fixed Hz bug support. Fixed …

bde60f5

…phase limit bug.

Added support for both matplotlib 1.x.x. and 2.x.x and fixed redrawin…

bc74a0a

…g issue.

Added docstring and unittest

1e3a925

removed bug where a pole or zero would be deleted if only 1 of them w…

94a0ea1

…as present

root locus smooth with zoom bug

c0e533e

Fixed zooming on plot. Now displays smoother root locus plot.

fe13ae1

Fixed paning on plot and clicking on the root locus plot while zoomed

2ba8277

Added unit test for rootlocus zoom functionality

c26187f

Fixed sisotool unittest

9962cea

Fixed frequency response unittest

938ae88

small change to sisotool test

9f13a77

small change to unittests

6e06a9c

fixed python 2 integer division error in false gain of rootlocus

cdb9f42

changed root locus test to a numerically more significant one.

90959bd

changed root locus test indices.

70ec8be

murrayrm added this to the 0.8.1 milestone Jun 30, 2018

Merge branch 'master' into sisotool_final

9f50e13

This was referenced Jul 14, 2018

Bode margins plot #199

Merged

Rlocus visual display of clicked point #204

Merged

murrayrm reviewed Jul 14, 2018

View reviewed changes

murrayrm modified the milestones: 0.8.1, 0.8.2 Jul 18, 2018

murrayrm mentioned this pull request Dec 28, 2018

Interactive plots in IPython notebooks #50

Open

Merge branch 'master' into sisotool_final

3e7cad6

Merge branch 'master' into sisotool_final

43d8b95

murrayrm added 2 commits April 11, 2019 21:33

Fix small typo from manual merge

03f87a3

fixed issues identified in review

17c4a95

murrayrm merged commit 908fabe into python-control:master Apr 16, 2019

murrayrm mentioned this pull request Jun 16, 2021

Two 'sgrid' functions when we only need one? #634

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Sisotool and dynamic root locus zoom #209

Sisotool and dynamic root locus zoom #209

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murrayrm commented Apr 12, 2019


		def sisotool(sys, kvect = None, xlim_rlocus = None, ylim_rlocus = None, plotstr_rlocus = 'b' if int(matplotlib.__version__[0]) == 1 else 'C0',rlocus_grid = False, omega = None, dB = None, Hz = None, deg = None, omega_limits = None, omega_num = None,margins_bode = True, tvect=None):

		"""Sisotool


		"""Sisotool

		Sisotool style collection of plots inspired by the matlab sisotool.

Sisotool and dynamic root locus zoom #209

Sisotool and dynamic root locus zoom #209

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