Fix multiple zero labels when using SymLogNorm #10129
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matplotlib/lib/matplotlib/ticker.py Line 2215 in 64874e5 matplotlib/lib/matplotlib/ticker.py Line 2353 in 64874e5 |
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The strategy of this PR can't work. If you run e.g. examples/pyplots/pyplot_scales.py with this PR applied, and move or zoom the symlog axes, the label at 0 disappears (because it is never redrawn).
I believe that @jklymak's idea is the correct approach.
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That’s a great point. I’ll spend some more time in the locator and the linear approximation around zero and see if there’s a good way to ensure only a single zero value.
…On Dec 29, 2017, 2:14 PM -0600, Antony Lee ***@***.***>, wrote:
@anntzer requested changes on this pull request.
The strategy of this PR can't work. If you run e.g. examples/pyplots/pyplot_scales.py with this PR applied, and move or zoom the symlog axes, the label at 0 disappears (because it is never redrawn).
I believe that @jklymak's idea is the correct approach.
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👍 That makes sense and looks like a reasonable fix. Could you add a test? I suspect creating a symlog axis and then asserting that there is only 0 zero label it in is the best approach (no need for an image test). The OP example is maybe a bit complex to trigger this, but as a last resort would be ok to use a test. |
Dismissing @tacaswell review as test now added per his wishes
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Just for completeness, the test is: from matplotlib import pyplot as plt
import matplotlib as mpl
fig, axes = plt.subplots(1, 2, True, True)
for i, ax in enumerate(axes):
im = ax.imshow([[0]], norm=mpl.colors.SymLogNorm(1e-5, vmin=-1, vmax=1))
cb = plt.colorbar(im, ax=ax)
# Clean up the labels
zero_labelled = False
for label in cb.ax.yaxis.get_ticklabels():
if label.get_text() == r'$\mathdefault{0}$':
if zero_labelled:
label.set_visible(False)
zero_labelled = True
plt.show() |
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Thanks a lot @Raab70! |
PR Summary
Use the previously unused position of a tick label to ensure that only a single zero label is rendered when using SymLogNorm. I store the first time a zero label is encountered and return blanks for all following zeros. The documentation on theticker.SymmetricalLogLocator.tick_valuesshows how these multiple zeros come to be through the linear approximation near zero.As per discussion below I have taken a different approach, trying to fix the root cause of the problem in the locator (
ticker.SymmetricalLogLocator.tick_values) so that the extra zero ticks are never created in the first place.Fixes #10122
PR Checklist