8000 FIX: allow colorbar mappable norm to change and do right thing · matplotlib/matplotlib@d7e098c · GitHub
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FIX: allow colorbar mappable norm to change and do right thing
FIX: stop colorbar from being a ScalarMappable, and deprecate common fcns FIX: allow norm limit to change and not change user-set ticks and format FIX: moved old ScalarMappable methods to a private method DOC: fix deprecation and tutorial DOC: api note
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‎doc/api/next_api_changes/2019-01-27-JMK.rst

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@@ -0,0 +1,12 @@
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`matplotlib.colorbar.ColorbarBase` is no longer a subclass of `.ScalarMappable`
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-------------------------------------------------------------------------------
3+
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This inheritance lead to a confusing situation where the
5+
`ScalarMappable` passed to `matplotlib.colorbar.Colorbar` (`~.Figure.colorbar`)
6+
had a ``set_norm`` method, as did the colorbar. The colorbar is now purely a
7+
slave to the `ScalarMappable` norm and colormap, and the old inherited methods
8+
`~matplotlib.colorbar.ColorbarBase.set_norm`,
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`~matplotlib.colorbar.ColorbarBase.set_cmap`,
10+
`~matplotlib.colorbar.ColorbarBase.set_clim` are deprecated, as are the
11+
getter versions of those calls. To set the norm associated with a colorbar do
12+
``colorbar.mappable.set_norm()`` etc.

‎lib/matplotlib/cm.py

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Original file line numberDiff line numberDiff line change
@@ -349,6 +349,13 @@ def set_norm(self, norm):
349349
Parameters
350350
----------
351351
norm : `.Normalize`
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353+
Notes
354+
-----
355+
If there are any colorbars using the mappable for this norm, setting
356+
the norm of the mappable will reset the norm, locator, and formatters
357+
on the colorbar to default.
358+
352359
"""
353360
if norm is None:
354361
norm = colors.Normalize()

‎lib/matplotlib/colorbar.py

Lines changed: 104 additions & 29 deletions
Original file line numberDiff line numberDiff line change
@@ -304,7 +304,47 @@ def tick_values(self, vmin, vmax):
304304
return ticks
305305

306306

307-
class ColorbarBase(cm.ScalarMappable):
307+
class _ColorbarMappableDummy(object):
308+
"""
309+
Private class to hold deprecated ColorbarBase methods that used to be
310+
inhereted from ScalarMappable.
311+
"""
312+
@cbook.deprecated("3.1", alternative="ScalarMappable.set_norm")
313+
def set_norm(self, norm):
314+
"""
315+
`.colorbar.Colorbar.set_norm` does nothing; set the norm on
316+
the mappable associated with this colorbar.
317+
"""
318+
pass
319+
320+
@cbook.deprecated("3.1", alternative="ScalarMappable.set_cmap")
321+
def set_cmap(self, cmap):
322+
"""
323+
`.colorbar.Colorbar.set_cmap` does nothing; set the norm on
324+
the mappable associated with this colorbar.
325+
"""
326+
pass
327+
328+
@cbook.deprecated("3.1", alternative="ScalarMappable.set_clim")
329+
def set_clim(self, cmap):
330+
"""
331+
`.colorbar.Colorbar.set_clim` does nothing; set the limits on
332+
the mappable associated with this colorbar.
333+
"""
334+
pass
335+
336+
@cbook.deprecated("3.1", alternative="ScalarMappable.get_cmap")
337+
def get_cmap(self):
338+
'return the colormap'
339+
return self.cmap
340+
341+
@cbook.deprecated("3.1", alternative="ScalarMappable.get_clim")
342+
def get_clim(self):
343+
'return the min, max of the color limits for image scaling'
344+
return self.norm.vmin, self.norm.vmax
345+
346+
347+
class ColorbarBase(_ColorbarMappableDummy):
308348
'''
309349
Draw a colorbar in an existing axes.
310350
@@ -371,7 +411,8 @@ def __init__(self, ax, cmap=None,
371411
if norm is None:
372412
norm = colors.Normalize()
373413
self.alpha = alpha
374-
cm.ScalarMappable.__init__(self, cmap=cmap, norm=norm)
414+
self.cmap = cmap
415+
self.norm = norm
375416
self.values = values
376417
self.boundaries = boundaries
377418
self.extend = extend
@@ -387,30 +428,26 @@ def __init__(self, ax, cmap=None,
387428
self.outline = None
388429
self.patch = None
389430
self.dividers = None
431+
self.locator = None
432+
self.formatter = None
390433
self._manual_tick_data_values = None
391434

392435
if ticklocation == 'auto':
393436
ticklocation = 'bottom' if orientation == 'horizontal' else 'right'
394437
self.ticklocation = ticklocation
395438

396439
self.set_label(label)
440+
self._reset_locator_formatter_scale()
441+
397442
if np.iterable(ticks):
398443
self.locator = ticker.FixedLocator(ticks, nbins=len(ticks))
399444
else:
400445
self.locator = ticks # Handle default in _ticker()
401-
if format is None:
402-
if isinstance(self.norm, colors.LogNorm):
403-
self.formatter = ticker.LogFormatterSciNotation()
404-
elif isinstance(self.norm, colors.SymLogNorm):
405-
self.formatter = ticker.LogFormatterSciNotation(
406-
linthresh=self.norm.linthresh)
407-
else:
408-
self.formatter = ticker.ScalarFormatter()
409-
elif isinstance(format, str):
446+
447+
if isinstance(format, str):
410448
self.formatter = ticker.FormatStrFormatter(format)
411449
else:
412-
self.formatter = format # Assume it is a Formatter
413-
# The rest is in a method so we can recalculate when clim changes.
450+
self.formatter = format # Assume it is a Formatter or None
414451
self.draw_all()
415452

416453
def _extend_lower(self):
@@ -432,7 +469,6 @@ def draw_all(self):
432469
Calculate any free parameters based on the current cmap and norm,
433470
and do all the drawing.
434471
'''
435-
436472
# sets self._boundaries and self._values in real data units.
437473
# takes into account extend values:
438474
self._process_values()
@@ -451,12 +487,6 @@ def draw_all(self):
451487

452488
def config_axis(self):
453489
ax = self.ax
454-
if (isinstance(self.norm, colors.LogNorm)
455-
and self._use_auto_colorbar_locator()):
456-
# *both* axes are made log so that determining the
457-
# mid point is easier.
458-
ax.set_xscale('log')
459-
ax.set_yscale('log')
460490

461491
if self.orientation == 'vertical':
462492
long_axis, short_axis = ax.yaxis, ax.xaxis
@@ -504,6 +534,20 @@ def _get_ticker_locator_formatter(self):
504534
else:
505535
b = self._boundaries[self._inside]
506536
locator = ticker.FixedLocator(b, nbins=10)
537+
538+
if formatter is None:
539+
if isinstance(self.norm, colors.LogNorm):
540+
formatter = ticker.LogFormatterSciNotation()
541+
elif isinstance(self.norm, colors.SymLogNorm):
542+
formatter = ticker.LogFormatterSciNotation(
543+
linthresh=self.norm.linthresh)
544+
else:
545+
formatter = ticker.ScalarFormatter()
546+
else:
547+
formatter = self.formatter
548+
549+
self.locator = locator
550+
self.formatter = formatter
507551
_log.debug('locator: %r', locator)
508552
return locator, formatter
509553

@@ -517,6 +561,24 @@ def _use_auto_colorbar_locator(self):
517561
and ((type(self.norm) == colors.Normalize)
518562
or (type(self.norm) == colors.LogNorm)))
519563

564+
def _reset_locator_formatter_scale(self):
565+
"""
566+
Reset the locator et al to defaults. Any user-hardcoded changes
567+
need to be re-entered if this gets called (either at init, or when
568+
the mappable normal gets changed: Colorbar.update_normal)
569+
"""
570+
self.locator = None
571+
self.formatter = None
572+
if (isinstance(self.norm, colors.LogNorm)
573+
and self._use_auto_colorbar_locator()):
574+
# *both* axes are made log so that determining the
575+
# mid point is easier.
576+
self.ax.set_xscale('log')
577+
self.ax.set_yscale('log')
578+
else:
579+
self.ax.set_xscale('linear')
580+
self.ax.set_yscale('linear')
581+
520582
def update_ticks(self):
521583
"""
522584
Force the update of the ticks and ticklabels. This must be
@@ -526,7 +588,6 @@ def update_ticks(self):
526588
# get the locator and formatter. Defaults to
527589
# self.locator if not None..
528590
locator, formatter = self._get_ticker_locator_formatter()
529-
530591
if self.orientation == 'vertical':
531592
long_axis, short_axis = ax.yaxis, ax.xaxis
532593
else:
@@ -1102,7 +1163,6 @@ def __init__(self, ax, mappable, **kw):
11021163
kw['boundaries'] = CS._levels
11031164
kw['values'] = CS.cvalues
11041165
kw['extend'] = CS.extend
1105-
#kw['ticks'] = CS._levels
11061166
kw.setdefault('ticks', ticker.FixedLocator(CS.levels, nbins=10))
11071167
kw['filled'] = CS.filled
11081168
ColorbarBase.__init__(self, ax, **kw)
@@ -1125,8 +1185,7 @@ def on_mappable_changed(self, mappable):
11251185
by :func:`colorbar_factory` and should not be called manually.
11261186
11271187
"""
1128-
self.set_cmap(mappable.get_cmap())
1129-
self.set_clim(mappable.get_clim())
1188+
_log.debug('colorbar mappable changed')
11301189
self.update_normal(mappable)
11311190

11321191
def add_lines(self, CS, erase=True):
@@ -1156,9 +1215,24 @@ def update_normal(self, mappable):
11561215
Update solid patches, lines, etc.
11571216
11581217
Unlike `.update_bruteforce`, this does not clear the axes. This is
1159-
meant to be called when the image or contour plot to which this
1160-
colorbar belongs changes.
1218+
meant to be called when the norm of the image or contour plot to which
1219+
this colorbar belongs changes.
1220+
1221+
If the norm on the mappable is different than before, this resets the
1222+
locator and formatter for the axis, so if these have been customized,
1223+
they will need to be customized again. However, if the norm only
1224+
changes values of *vmin*, *vmax* or *cmap* then the old formatter
1225+
and locator will be preserved.
11611226
"""
1227+
1228+
_log.debug('colorbar update normal %r %r', mappable.norm, self.norm)
1229+
self.mappable = mappable
1230+
self.set_alpha(mappable.get_alpha())
1231+
self.cmap = mappable.cmap
1232+
if mappable.norm != self.norm:
1233+
self.norm = mappable.norm
1234+
self._reset_locator_formatter_scale()
1235+
11621236
self.draw_all()
11631237
if isinstance(self.mappable, contour.ContourSet):
11641238
CS = self.mappable
@@ -1180,15 +1254,16 @@ def update_bruteforce(self, mappable):
11801254
# properties have been changed by methods other than the
11811255
# colorbar methods, those changes will be lost.
11821256
self.ax.cla()
1257+
self.locator = None
1258+
self.formatter = None
1259+
11831260
# clearing the axes will delete outline, patch, solids, and lines:
11841261
self.outline = None
11851262
self.patch = None
11861263
self.solids = None
11871264
self.lines = list()
11881265
self.dividers = None
1189-
self.set_alpha(mappable.get_alpha())
1190-
self.cmap = mappable.cmap
1191-
self.norm = mappable.norm
1266+
self.update_normal(mappable)
11921267
self.draw_all()
11931268
if isinstance(self.mappable, contour.ContourSet):
11941269
CS = self.mappable

‎lib/matplotlib/tests/test_colorbar.py

Lines changed: 55 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -4,10 +4,10 @@
44
from matplotlib import rc_context
55
from matplotlib.testing.decorators import image_comparison
66
import matplotlib.pyplot as plt
7-
from matplotlib.colors import BoundaryNorm, LogNorm, PowerNorm
7+
from matplotlib.colors import BoundaryNorm, LogNorm, PowerNorm, Normalize
88
from matplotlib.cm import get_cmap
9-
from matplotlib.colorbar import ColorbarBase
10-
from matplotlib.ticker import LogLocator, LogFormatter
9+
from matplotlib.colorbar import ColorbarBase, _ColorbarLogLocator
10+
from matplotlib.ticker import LogLocator, LogFormatter, FixedLocator
1111

1212

1313
def _get_cmap_norms():
@@ -442,23 +442,69 @@ def test_colorbar_renorm():
442442
fig, ax = plt.subplots()
443443
im = ax.imshow(z)
444444
cbar = fig.colorbar(im)
445+
assert np.allclose(cbar.ax.yaxis.get_majorticklocs(),
446+
np.arange(0, 120000.1, 15000))
447+
448+
cbar.set_ticks([1, 2, 3])
449+
assert isinstance(cbar.locator, FixedLocator)
445450

446451
norm = LogNorm(z.min(), z.max())
447452
im.set_norm(norm)
448-
cbar.set_norm(norm)
449-
cbar.locator = LogLocator()
450-
cbar.formatter = LogFormatter()
451-
cbar.update_normal(im)
453+
assert isinstance(cbar.locator, _ColorbarLogLocator)
454+
assert np.allclose(cbar.ax.yaxis.get_majorticklocs(),
455+
np.logspace(-8, 5, 14))
456+
# note that set_norm removes the FixedLocator...
452457
assert np.isclose(cbar.vmin, z.min())
458+
cbar.set_ticks([1, 2, 3])
459+
assert isinstance(cbar.locator, FixedLocator)
460+
assert np.allclose(cbar.ax.yaxis.get_majorticklocs(),
461+
[1.0, 2.0, 3.0])
453462

454463
norm = LogNorm(z.min() * 1000, z.max() * 1000)
455464
im.set_norm(norm)
456-
cbar.set_norm(norm)
457-
cbar.update_normal(im)
458465
assert np.isclose(cbar.vmin, z.min() * 1000)
459466
assert np.isclose(cbar.vmax, z.max() * 1000)
460467

461468

469+
def test_colorbar_format():
470+
# make sure that format is passed properly
471+
x, y = np.ogrid[-4:4:31j, -4:4:31j]
472+
z = 120000*np.exp(-x**2 - y**2)
473+
474+
fig, ax = plt.subplots()
475+
im = ax.imshow(z)
476+
cbar = fig.colorbar(im, format='%4.2e')
477+
fig.canvas.draw()
478+
assert cbar.ax.yaxis.get_ticklabels()[4].get_text() == '6.00e+04'
479+
480+
# make sure that if we change the clim of the mappable that the
481+
# formatting is *not* lost:
482+
im.set_clim([4, 200])
483+
fig.canvas.draw()
484+
assert cbar.ax.yaxis.get_ticklabels()[4].get_text() == '8.00e+01'
485+
486+
# but if we change the norm:
487+
im.set_norm(LogNorm(vmin=0.1, vmax=10))
488+
fig.canvas.draw()
489+
assert (cbar.ax.yaxis.get_ticklabels()[0].get_text() ==
490+
r'$\mathdefault{10^{-1}}$')
491+
492+
493+
def test_colorbar_scale_reset():
494+
x, y = np.ogrid[-4:4:31j, -4:4:31j]
495+
z = 120000*np.exp(-x**2 - y**2)
496+
497+
fig, ax = plt.subplots()
498+
pcm = ax.pcolormesh(z, cmap='RdBu_r', rasterized=True)
499+
cbar = fig.colorbar(pcm, ax=ax)
500+
assert cbar.ax.yaxis.get_scale() == 'linear'
501+
502+
pcm.set_norm(LogNorm(vmin=1, vmax=100))
503+
assert cbar.ax.yaxis.get_scale() == 'log'
504+
pcm.set_norm(Normalize(vmin=-20, vmax=20))
505+
assert cbar.ax.yaxis.get_scale() == 'linear'
506+
507+
462508
def test_colorbar_get_ticks():
463509
with rc_context({'_internal.classic_mode': False}):
464510

‎tutorials/colors/colorbar_only.py

Lines changed: 4 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -8,12 +8,10 @@
88
Customized Colorbars
99
====================
1010
11-
:class:`~matplotlib.colorbar.ColorbarBase` derives from
12-
:mod:`~matplotlib.cm.ScalarMappable` and puts a colorbar in a specified axes,
13-
so it has everything needed for a standalone colorbar. It can be used as-is to
14-
make a colorbar for a given colormap; it does not need a mappable object like
15-
an image. In this tutorial we will explore what can be done with standalone
16-
colorbar.
11+
`~matplotlib.colorbar.ColorbarBase` puts a colorbar in a specified axes,
12+
and can make a colorbar for a given colormap; it does not need a mappable
13+
object like an image. In this tutorial we will explore what can be done with
14+
standalone colorbar.
1715
1816
Basic continuous colorbar
1917
-------------------------

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