ENH: adjustable colorbar ticks by jklymak · Pull Request #9903 · matplotlib/matplotlib · GitHub

PR Summary

This PR changes colorbar to draw from self.vmin to self.vmax instead of from 0 to 1 so that AutoTickLocator can work. Only modifies ticks if no boundaries are specified (i.e. contours).

See #9246

example:

import matplotlib.pyplot as plt
import matplotlib.colors as mcolors
import numpy as np

X = np.random.randn(32, 32)


fig, ax = plt.subplots(2, 2, figsize=(5, 5), tight_layout=True)
for nn, shrink in enumerate([1., 0.4]):
    for mm, log in enumerate([False, True]):
        if log:
            norm = mcolors.LogNorm()
            Y = 10**X
        else:
            norm = None
            Y = X
        pc = ax[nn, mm].pcolormesh(Y, norm=norm)
        ax[nn, mm].set_xticks([])
        ax[nn, mm].set_yticks([])
        fig.colorbar(pc, ax=ax[nn,mm], shrink=shrink, extend='both')

plt.show()
fig.savefig('ExampleCBOld.png')

before:

after:

PR Checklist

Test/get to work LogNorm
Has Pytest style unit tests
Code is PEP 8 compliant
Added an entry to doc/users/next_whats_new/ if major new feature (follow instructions in README.rst there)
Documented in doc/api/api_changes.rst if API changed in a backward-incompatible way

OK, this failed enough tests that there are a bunch more edge cases I need to consider. Good thing there are tests. I'll probably re-do this from scratch and try to make it less invasive. I do think this is reasonable for 2.2, though, because I'll keep plugging away at it.

This is redone, and much simpler now. 4 image files had to be changed...

Ping @efiring LogNorm() now works. I'm too lazy to do SymLogNorm() (well actually I disapprove of that normalization as a valid thing to do to data), but someone could easily figure it out.

The diff looks worse than it is because I moved a bit of code around.

Much of this was jut factored out of _ticker() But note the new locators for LogNorm and the fallback...

Some questions/comments, looks like this is good overall though

Shouldn't the docstring line up with the left of the quote marks?

Why are there args and kwargs here if they're not used? Can this also get a docstring (just for the colorbar parameter is probably fine)

Same as above comment on __init__

Is this old debug code that needs to be removed?

and only the yscale be log here?

They both need to be log to make the aspect kwarg work properly (... or we could do a bunch of math and make the X values make the aspect ratio right.)

This method could do with a quick comment underneath to explain what it does.

This commented out line can go

Pushed to 3.0 as this isn't urgent. But I think it'd be easy to put in 2.2 if someone wants to dive in and re-milestone...

rebased

@dstansby I think I addressed all your concerns.
@efiring requesting a review from you (though no rush) as this is your bailiwick...

Old review

The before-and-after comparison looks great, but tests seem to be failing now.

Yeah, its just the streamplot image test at 0.036 tolerance. I'll try to track it down. It passes on my machine and I took the text out so it can't be freetype. Grrrr.

I'm not sure that this is the right place to tell this, but I recently wrote a detailed instruction on colorbar in matplotlib which might contribute for improving tutorials about colorbar.
https://qiita.com/skotaro/items/01d66a8c9902a766a2c0
It's only in Japanese for the moment but I think you can get the ideas from figures and sample codes. Main topics are 1. Anatomy of a colorbar, 2. Putting a colorbar at the right place with the right size, and 3. Changing ticker into log scale nicely. It's not comprehensive but I think it still helps users puzzled by colorbar.

After writing it, fortunately or not, I found this PR which seems to change colorbar's behavior significantly (no pseudo minor ticks, no normalization of vmin/vmax to 0/1, for example). Actually these modified behaviors are parts of the main topics in my instruction. Then I'm wondering whether I should translate the introduction as it is into English and make a PR to improve docs for the current behavior of colorbar (about cbar.ticker, especially), or I should wait for this PR to be implemented in, say, next rc version and revise the instruction to catch up the new behaviors. What do you think?

@skotaro Sounds like we had some similar difficulties with colorbars. I will push in the near future for this PR to get in, but it won’t be part of the distribution until 3.0 (July/Aug).

You may want to checkout constrained layout in 2.2Rc1 for easier colorbar placement. That doesn’t preclude a tutorial that explains how to fix things manually, but I’d suggest such a tutorial should at least reference the automated methods.

The problem with the doc build is that after the merge, the sphinx conf.py exclude_patterns list is out of sync with the location where you are putting your users/whats_new file.
It looks like this is a bug in master: there are directories users/prev_whats_new and users/next_whats_new, but exclude_patterns = ['api/api_changes/*', 'users/whats_new/*'].

Somehow the doc build didn't like the name I had for the whats-new file. Works fine now. 🤷‍♂️

You can use the long_axis, short_axis here, too. Initialize them prior to the _use_auto_colorbar_locator check.
Instead of ax.set_yticklabels you can use the equivalent short_axis.set_ticklabels, etc.

extra space

Is there a particular need to include the signature?

Need to check that some ticks are labelled...

Fixed. LogLocator works fine here.

@jklymak Is there an obvious reason why the ticks of the colorbar in the bottom right panel are not symmetrical (in log space) around 1 (e.g. [1e3, 1e0, 1e-3], instead of [1e2, 1e-1]), while the old one were “quite” symmetrical?

@afvincent because the LogLocator only returned two tick marks as being able to fit and it chose those? Its just using the default LogLocator - i.e. if you had a normal yaxis that size, those are the ticks you'd get.

@skotaro Are you still interested in including your (extensive!) colorbar tutorial into the mpl docs? Even if it needs to be updated following this PR and/or to take constrained_layout into account, feel free to open an early issue/PR to track the work.

@anntzer @skotaro please note the start of this at https://matplotlib.org/devdocs/gallery/subplots_axes_and_figures/colorbar_placement.html#sphx-glr-gallery-subplots-axes-and-figures-colorbar-placement-py

tacaswell added this to the v2.2 milestone Dec 1, 2017

jklymak force-pushed the enh-colorbar-ticks branch 2 times, most recently from 9d1146d to 5c48c10 Compare December 2, 2017 06:48

jklymak changed the title WIP: ENH: adjustable colorbar ticks ENH: adjustable colorbar ticks Dec 2, 2017

jklymak force-pushed the enh-colorbar-ticks branch from 5c48c10 to 1d4160c Compare December 2, 2017 21:58

jklymak force-pushed the enh-colorbar-ticks branch from 338c0a1 to a31cadd Compare December 19, 2017 20:55

jklymak commented Dec 19, 2017

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jklymak mentioned this pull request Dec 20, 2017

Blank colorbars for high dynamic range LogNorm imshow plots #10051

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dstansby previously requested changes Dec 24, 2017

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jklymak force-pushed the enh-colorbar-ticks branch from 452e401 to 5972691 Compare December 24, 2017 18:00

dstansby self-assigned this Dec 24, 2017

jklymak requested review from efiring and removed request for efiring January 10, 2018 03:38

jklymak modified the milestones: v2.2, v3.0 Jan 10, 2018

jklymak mentioned this pull request Feb 4, 2018

[ENH] Unit support for ScalarMappables #7383

Open

jklymak force-pushed the enh-colorbar-ticks branch from 5972691 to 402b4d3 Compare February 4, 2018 18:15

jklymak requested a review from efiring February 4, 2018 18:18

jklymak mentioned this pull request Feb 19, 2018

FIX: No rcparam minor ticks in colorbar #8358 #10530

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6 tasks done

jklymak force-pushed the enh-colorbar-ticks branch 5 times, most recently from 651d609 to 2c33640 Compare March 18, 2018 04:58

efiring reviewed Mar 18, 2018

View reviewed changes

jklymak force-pushed the enh-colorbar-ticks branch from 2c33640 to 252ef97 Compare March 18, 2018 15:23

ENH: colorbar ticks adjustable to colorbar size

52e5d81

jklymak force-pushed the enh-colorbar-ticks branch from 6bdc427 to 52e5d81 Compare March 18, 2018 16:01

efiring approved these changes Mar 18, 2018

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anntzer reviewed Mar 19, 2018

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jklymak commented Mar 19, 2018

View reviewed changes

FIX: add loglocator for minor colorbar

b74c0fd

jklymak added the status: needs review label Mar 19, 2018

dopplershift approved these changes Mar 22, 2018

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dopplershift merged commit dbfc79c into matplotlib:master Mar 22, 2018

Dih5 mentioned this pull request Mar 23, 2018

Minor ticks on log-scale colorbar are not cleared #8358

Closed

QuLogic removed the status: needs review label Mar 23, 2018

This was referenced Sep 18, 2018

Incorrect placement of Colorbar ticks using LogNorm #12155

Closed

FIX: colorbar re-check norm before draw for autolabels #12159

Merged

anntzer mentioned this pull request Oct 12, 2018

inconsistent colorbar tick labels for LogNorm #12488

Closed

ImportanceOfBeingErnest mentioned this pull request Oct 17, 2018

colorbar resizes in animation #12550

Closed

ImportanceOfBeingErnest mentioned this pull request Oct 31, 2018

using AxesImage.set_clim() shrinks the colorbar #12682

Closed

+                      This locator is just a `.MaxNLocator` except the min and max are
+                      clipped by the norm's min and max (i.e. vmin/vmax from the
+                      image/pcolor/contour object).  This is necessary so ticks don't
+                      extrude into the "extend regions".

                       self._config_axes(X, Y)
                       if self.filled:
                           self._add_solids(X, Y, C)
+                      # self._set_view_limits()

+                          if (isinstance(self.norm, colors.LogNorm)
+                                  and self._use_adjustable()):
+                              ax.set_xscale('log')
+                              ax.set_yscale('log')

-                          else:
-                              b = self._boundaries[self._inside]
-                              locator = ticker.FixedLocator(b, nbins=10)
+                      # locator, formatter = _get_ticker_locator_formatter()

-                          ax.xaxis.get_major_formatter().set_offset_string(offset_string)
+                          _log.debug('Using fixed locator on colorbar')
+                          ticks, ticklabels, offset_string = self._ticker(locator, formatter)
+                          if self.orientation == 'vertical':

+              Colorbar ticks now adjust for the size of the colorbar if the
+              colorbar is made from a mappable that is not a contour or
+              doesn't have  a BoundaryNorm, or boundaries are not specified.

+                  def __init__(self, colorbar):
+                      """
+                      _ColorbarAutoLocator(colorbar)

+                          if type(self.norm) == colors.LogNorm:
+                              long_axis.set_minor_locator(_ColorbarLogLocator(self,
+                                          base=10., subs='auto'))
+                              long_axis.set_minor_formatter(ticker.NullFormatter())


		self._set_label()

		def _get_ticker_locator_formatter(self):


		self._set_label()

		def _get_ticker_locator_formatter(self):

ENH: adjustable colorbar ticks by jklymak · Pull Request #9903 · matplotlib/matplotlib · GitHub

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ENH: adjustable colorbar ticks - #9903

ENH: adjustable colorbar ticks#9903dopplershift merged 2 commits intomatplotlib:mastermatplotlib/matplotlib:masterfrom jklymak:enh-colorbar-ticksjklymak/matplotlib:enh-colorbar-ticksCopy head branch name to clipboard

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ENH: adjustable colorbar ticks#9903
dopplershift merged 2 commits into
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jklymak:enh-colorbar-ticks

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