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[ENH]: Support for custom/special ticks without complex workarounds #22262
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If you need to manually label ticks because they are not part of the formatter then: ax.set_yticks([ys1[-1], ys2[-1], ys3[-1]], labels=[ys1[-1], ys2[-1], ys3[-1]]) should work, plus or minus some formatting. |
Yes, that is correct, you cannot mix and match custom and automatic ticks like this. If you want custom ticks, you must specify all the ticks - we don't allow more than one Locator or Formatter on an axis. This is veering into user help, but you can easily add a secondary axis, and put whatever ticks you want on that. That is the approach I would take rather than trying to put new API on the already complicated axis ticker API. See https://matplotlib.org/stable/gallery/subplots_axes_and_figures/secondary_axis.html |
Would it make sense (and be possible) that the I guess the empty string comes from here (or the corresponding non-Mathtext lines): matplotlib/lib/matplotlib/ticker.py Lines 1081 to 1084 in 612cfae
and somehow bypassing that should make things work more as may be expected. |
@oscargus the major flaw of the Locator/Formatter dance is that the Formatter doesn't know anything about the Locator or the other ticks being formatted. Fixing that is a medium term project, but it is a tricky one if back compatibility is to be maintained. Again, my recommended solution here is to use a secondary axis, which can also conveniently be on the right hand side, so it doesn't over plot on the scale on the left:
(If you want, it can be on the "left" as well, which is exactly what is being asked for here, but I really think that suffers from readability concerns) Whether one calls this a "complex workaround" or not, it is logically much easier than trying to track manual and custom ticks, each with different formatting etc. |
@jklymak Regarding the solution with the secondary axis: in my original use case, I had already used my secondary y axis for another unit scale, like this: so that approach wouldn't work for me. In the end I used an From what I am gathering, solving this issue (i.e. adding special ticks to an axis – short of setting all ticks manually) straight on without wrestling the API would require the user to provide their own tick |
You can have as many secondary axis-es as you want. Adding extra ticks is not straightforward, so while I'm sure a clever API could be developed, I'm not convinced it would be worth it given the many other ways to annotate plots. |
That should typically be very welcome (as far as my experience goes, not an official statement). |
In general document improvements are very welcome. In this case perhaps an example of one does not already exist. Perhaps the docs for set_x/yticks should be made more explicit that they replace the locator (and maybe formatter) for the axis with a Fixedlocator and FixedFormatter and a note that they do not change the minor locator or formatter |
…22262 (#22270) * Expanded documentation of Axis.set_ticks() * Fix flake8 W293 (blank line contains whitespace) warnings * Expanded the documentation even more based on discussion in issue #22262 * Update lib/matplotlib/axis.py - @jklymak rewording Co-authored-by: Jody Klymak <jklymak@gmail.com> * Reduced verbosity of doc by @jklymak 's suggestion. * On second thought, the previous wording could be seen as very ambiguous. * Update set_ticks docstring by @timhoffm compromise suggestion Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> * Removed extra sentence as per @timhoffm review * Blank line whitespace issue crept up again * Update lib/matplotlib/axis.py as per correction by @timhoffm Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> Co-authored-by: unknown <> Co-authored-by: Jody Klymak <jklymak@gmail.com> Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
_axstack whitespace _parent._axstack move clear functions into figurebase clear subfigures first Clear child subfigures tests move property back to init changelog reduce changelog TEST: partial subfig clearing Clear all children subfigs in parent Clear toolbars only in Figure Restore whitespace on :684 flake8 old comment TITLE UNDERLINE Expire mathttext-related deprecations Fixed review comments and a few more removals Use PNG image as the icon for Tk plot windows Fix loading user-defined icons for Tk toolbar Co-Authored-By: Elliott Sales de Andrade <quantum.analyst@gmail.com> Prevent tooltips from overlapping buttons in NavigationToolbar2Tk Update doc/api/next_api_changes/behavior/22135-JSS3.rst Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> Fix loading user-defined icons for Qt plot window Update both zoom/pan states on wx when triggering from keyboard. Previously, typing "o" and "p" on a wx window would result in both the zoom and the pan button being pressed at the same time. Fix that by relying on the same strategy as all other backends. Switch transOffset to offset_transform. Note that most APIs *previously* already accepted *offset_transform* as kwarg, due to the presence of the `set_offset_transform` setter. Prefer that name (shortening it to `offset_trf` for local variables). Backcompat for the old `transOffset` name is kept in most places by introducing a property alias. Started deprecating tight_bbox and tight_layout Recreated deprecated files and changed references Fix drawing animated artists changed in selector callback Fix getting tuple of animated artists; add comments and test Use list comprehension instead of filter Fix z_order Improve docstring and add comments Ensure log formatters use Unicode minus Fixes matplotlib#21540 FIX: better repr for subgridspecs FIX: add test for identical subgridspec FIX Use a fixture for widget test axes Improved coverage of mathtext and removed unused code Removed dev from 3.10-version DOC: explain too many ticks DOC: artist extent Update doc/users/faq/howto_faq.rst Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> Apply suggestions from code review Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> FIX: streamline examples DOC: add new example Update doc/users/faq/howto_faq.rst Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> Apply suggestions from code review Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> FIX: macosx check case-insensitive app name Only check for "python" case insensitive to match either Python or pythonw. Fix typo in `axhline` docstring Removed unused variables etc. Passed on sides and pad_to Use standard toolbar in wx. The previous approach manually positioned the toolbar to have it at the bottom of the window, but this can in fact be achieved just with style=wx.TB_BOTTOM. Removing manual sizing of the toolbar also fixes a bug previously present on Windows, whereby a `set_size_inches` reducing the size of the canvas would *not* reduce the window width, likely because it was forced to its max value by the toolbar's explicit size. Expire axes_grid1/axisartist deprecations. Clean up 3d plot box_aspect zooming linting Cleanup Make zoom and dist private attrs Deprecate Axes3D.dist Deprecate Axes3D.dist DOC: Fix upstream URL for merge in CircleCI DOC: Add hatch API to reference DOC: Document default cap styles - remove '(default)' from cap style demo as this is only true for Line2D and the default rcParameters - document default cap styles for Line2D and Patch in their cap style setters - document default cap style for GraphicsContextBase in the same way as it's already done for joinstyle Factor out underline-thickness lookups in mathtext. Just adding a small helper function. Fix merge Update _formlayout.py Bump minimum NumPy to 1.19 Fix name typo in API changes DOC: git:// is deprecated. See https://github.blog/2021-09-01-improving-git-protocol-security-github/ Today is a brownout day. I removed the sentence that git:// is RO and https:// is RW as you soon won't be able to use git:// Personally I use https:// as RO and ssh:// as RW, but I understand it might not be convenient on windows. Stop sorting artists in Figure Options dialog With matplotlib#18216, the order that artists are added to an Axes is their canonical order. The dialog should not be sorting them in some other manner. Additionally, this fixes a bug in that `apply_callback` indexes back to the original list, which means that changes will be made to the *wrong* artist if sorting actually occurred. It also makes the legend almost entirely wrong as well. See https://discourse.matplotlib.org/t/bug-on-re-generate-automatic-legend-of-matplotlib-figure-property/22511 Document ArtistList DOC: Document default join style in the same way as the default cap styles. Jointly track x and y in PolygonSelector. It's easier to track them in a single list. Also init _selection_artist and _polygon_handles with empty arrays, as there's no reason to pretend that they start with 0, 0. On the other hand, _xys does need to start as a non-empty array as the last point gets updated as being the cursor position. Verify that lib/src is not changed on -doc backports ci: Use released version to build v*-doc branches Fix typo in `tutorials/intermediate/arranging_axes.py` Trivial doc fix to annotations tutorial. Initially I just wanted to capitalize "matplotlib", but the wording was a bit awkward too, so... ENH: implement and use base layout_engine for more flexible layout. FIX: typo Remove some unnecessary getattrs. Figures always have a canvas attached (even if it's just a FigureCanvasBase), and canvases always have a "manager" attribute (which may be None). Canvases also always have a "toolbar" attribute (which also may be None). Altogether this allows avoiding a couple of getattrs. FIX: Return value instead of enum in get_capstyle/_joinstyle for MarkerStyle and Patch (as do Line2D, Collections and GraphicsContextBase) (1) turn off the grid after creating colorbar axes (2) added a test Cleanup "anatomy of a figure" No visual change. Improve formatting of "Anatomy of a figure" - Adapt margins - Reduce figure border width (still thick but not massive) - fontfamily: make code monospace - slightly move annotations to better places Run wheel builds on PRs when requested by a label Fix typos Deprecate cleared kwarg to get_renderer. This makes it easier for to mock the agg backend (e.g., in mplcairo). Note that this is anyways only a shorthand for calling a method (`.clear()`) on the renderer itself, so just issuing that call is just as simple, more explicit, and can be done even when one just has access to the renderer and not to the canvas (an admittedly rather hypothetical case). Improve ft2font error reporting. This prints out human-readable error messages for failures. As an example, `FT2Font("setup.py")` now raises ``` RuntimeError: In FT2Font: Can not load face (unknown file format; error code 0x2) ``` Ensure that all toolbar (old/new) subclasses can be init'ed consistently i.e. with the same signature: with `canvas` as sole arg for the old-style toolbars, with `toolmanager` as sole arg for the new ones. Subclasses that explicitly support setting a parent widget keep that support (except for gtk, which stashed that in the `.win` attribute but never used it), but that argument is always optional now; the default is the canvas' parent. The goal is to later replace all _get_toolbar implementations by a simple call (always with the same signature (dependent on the value of rcParams["toolbar"])) to the correct class in the FigureManagerBase constructor. DOC: More capitalization of Axes In line with matplotlib#18726. Triggered by matplotlib#22242. Started deprecating afm, fontconfig_pattern, and type1font Recreated deprecated files and changed references DOC: add dropdown DOC: add dropdown Fix topbar DOC: Add all the releases Just last point releases before 3.0 DOC: update release_guide DOC: rename versions [skip azp] [skip appveyor] [skip actions] BLD: pin sphinx data theme [skip actions] [skip appveyor] [skip azp] Add some tests for minspan{x,y} in RectangleSelector Skip tests on the -doc branches DOC: fix version switcher json [skip actions] [skip appveyor] [skip azp] DOC: fix version switcher [skip actions] [skip appveyor] [skip azp] FIX Fix Qt enum access. This was missed in the global fixing of enums for PyQt6 (now using _enum everywhere). To trigger, try to interactively save a figure but input an invalid format, e.g. "foo.bar". MNT: deprecate filled parameter to colorbar The *filled* kwarg doesn't directly do anything and filling is completely controlled by the mappable. OTOH, maybe we want to reinstate the ability of *filled* to fill contours? Deprecate colorbar.draw_all. Merge main and "other" params docs in colorbar.make_axes. `colorbar.make_axes` (and `make_axes_gridspec`) are low-level enough that it's not worth the complexity in docstring interpolation to split out "main" parameters and "other" parameters, when the docstring of the more commonly used `plt.colorbar` smashes them together. (Also, `pad` is not really much more low-level than `shrink` or `aspect`...) Numpydocify _colormap_kw_doc and use it in Colorbar too. Specify the focal length for 3d plots Create a gallery example showing the different proj_type options Typo Test fix, example fix, and linting What's new, example fix Merge conflict Offset zooming of focal length Code review comments, consolidate projection functions Try and fix zooming Try to fix the focal length zooming Update example Cleanup example cleanup more example tweaks more example tweak swap plot order Enforce a positive focal length focal lentgh tests flake8 linting docstring tweak Code review changes Make focal_length a private attr linting More code review changes and tests Additional code review changes Disalbe showing cursor data on a QuadMesh by default Give the Tk toolbar buttons a flat look Simplify FontProperties.copy(). Expanded documentation of Axis.set_ticks as per discussion in issue matplotlib#22262 (matplotlib#22270) * Expanded documentation of Axis.set_ticks() * Fix flake8 W293 (blank line contains whitespace) warnings * Expanded the documentation even more based on discussion in issue matplotlib#22262 * Update lib/matplotlib/axis.py - @jklymak rewording Co-authored-by: Jody Klymak <jklymak@gmail.com> * Reduced verbosity of doc by @jklymak 's suggestion. * On second thought, the previous wording could be seen as very ambiguous. * Update set_ticks docstring by @timhoffm compromise suggestion Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> * Removed extra sentence as per @timhoffm review * Blank line whitespace issue crept up again * Update lib/matplotlib/axis.py as per correction by @timhoffm Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> Co-authored-by: unknown <> Co-authored-by: Jody Klymak <jklymak@gmail.com> Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> MNT: make colorbars locators and formatters properties TST: test setters and getters in colorbar DOC: improve crosslinking for docs FIX: small fixes DOC: fix property docstrings FIX: minorformatter None Removed unused code Fixed repr for SecondaryAxis and increase coverage for axes/_base.py Apply suggestions from code review Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> Display bad format string in error message. I had something like `for i in range(n): plot(..., f"oC{i}")` which works for n up to 10, but for greater values one gets "oC10" which is not supported (which is reasonable, as some single-digit strings are actually *marker* abbreviations); mentioning the full format string in the error message ("Unrecognized character 0 in format string 'oC10'") makes it clearer. FIX: bury import of matplotlib.font_manager We need to ensure that the sub-module matplotlib.font_manager is imported when it is used in SclarFormater, however if we import it at the top level we will get circular imports. closes matplotlib#22305 In mpl_toolkits, use the same floating point slop as for standard ticks. Standard ticks use _interval_contains_close (in Axis._update_ticks); do the same in mpl_toolkits and deprecate the custom slops delta1, delta2 (if such knobs are really needed, we should try to have the same API in the main library anyways). FIX: use window_extent instead Add set_cursor method to FigureCanvasTk Don't warn on grid removal deprecation is grid is hidden Fixes matplotlib#21723. See matplotlib#21723 (comment) for a full desciption of motivation and edge cases. Modify example for x-axis tick labels at the top Primarily describe how to do this for a single Axes (using `tick_params`). Only mention the `rcParams` in a note. Globally changing `rcParams` is usually not a good idea and should not be demonstrated. The whole topic of `rcParams` (global, context, matplotlibrc) is too long to be discussed here and not the focus of the example. Remove Axes sublist modification from docs Make bar of pie example more explicit ... by saving and using the results from Axes method calls. Also, replace the colour palette in the bar chart. Respect `position` argument in Tk toolmanager Set focus properly to ensure mouse events get delivered to Tk canvas Rework/fix Text layout cache. Instead of caching the text layout based on a bunch of properties, only cache the computation of the text's metrics, which 1) should be the most expensive part (everything else in _get_layout is relatively simple iteration and arithmetic) and 2) depends on fewer implicit parameters. In fact, the old cache key was insufficient in that it would conflate usetex and non-usetex strings together, even though they have different metrics; e.g. with the (extremely artificial) example ```python figtext(.1, .5, "foo\nbar", size=32) # (0) figtext(.1, .5, "foo\nbar", usetex=True, size=32, c="r", alpha=.5) # (1) figtext(.3, .5, "foo\nbar", usetex=True, size=32, c="r", alpha=.5) # (2) ``` the linespacing of the first usetex string (1) would be "wrong": it is bigger that the one of the second usetex string (2), because it instead reuses the layout computed for the non-usetex string (0). The motivation is also to in the future let the renderer have better control on cache invalidation (with a yet-to-be-added renderer method), e.g. multiple instances of the same renderer cache could share the same layout info. Rename outdated seaborn styles. They are kept available under a versioned name for backcompat. dangling clf Silently discard blits if bbox is outside canvas Custom cap widths in box and whisker plots in bxp() and boxplot() Add pre-commit config and dev instructions Update pre-commit hooks rst format Disable autofixes on PRs Unless manually triggered. See https://pre-commit.ci/#configuration add pre-commit to environment.yml Slow down autoupdate schedule alphabetize Add sentence about where pre-commit config is Add excludes to pre-commit config Otherwise end of lines of test images will get fixed, this also ignores all the prev_whats_new and prev_api_changes as well as vendored components (agg, gitwash) pre-comit config CI: ban coverage 6.3 that may be causing random hangs in fork test
Fixed by #22270, AFAICT. Feel free to ping for reopening otherwise. |
Problem
There is no direct, user-friendly method to add custom/special ticks. Existing methods can lead to surprising results and I have found little official guidance in the documentation that would account for this.
From what I have seen in the examples gallery and on the Internet, most solutions rely on
Axes.set_xticks
orAxes.set_yticks
. These methods can fail silently (and very frustratingly) when attempting to work with e.g. a semilog plot.Example of what would be expected behaviour with user set ticks (using ordinary
plot
):outputs

Now, trying the same with
Axes.semilogy
instead ofAxes.plot
:silently fails to produce labelled ticks:

I have deduced that the problem lies with
LogFormatterSciNotation
, which doesn't produce a tick label when presented with user-provided values.My workaround includes subclassing and substituting the formatter:
Given these complications that necessitate a not completely trivial workaround, I believe it would be helpful to introduce explicit support for user-provided special ticks (in parallel to automatically-generated ticks). Other software e.g. OriginLab/OriginPro offers such a feature out of the box.
Proposed solution
At the very least, amend documentation of
Axes.set_xticks
/Axes.set_yticks
to state that the results also depend on theFormatter
of the axis, which may ignore the ticks which were added manually. Current documentation claiming thatIf not set, the labels show the data value.
is misleading when this isn't mentioned.Add a gallery example that shows how to use special ticks, with more emphasis on such edge cases as can occur with e.g. log plots.
If possible, create new API methods that would explicitly support manually-added special ticks, so that the user does not have to worry about making the axis formatter work with the custom ticks. This API could be connected with the
hlines
/vlines
method to give horizontal/vertical lines ending in a special tick, which may be very helpful in some contexts.The text was updated successfully, but these errors were encountered: