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Deprecate parameters to colorbar which have no effect. #16051

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Merged
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Jan 3, 2020
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Deprecate parameters to colorbar which have no effect. #16051

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10 changes: 10 additions & 0 deletions doc/api/next_api_changes/deprecations.rst
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Expand Up @@ -96,3 +96,13 @@ colormapping such as ``scatter()`` and ``imshow()`` is deprecated.
Inestead of ``norm=LogNorm(), vmin=min_val, vmax=max_val`` pass
``norm=LogNorm(min_val, max_val)``. *vmin* and *vmax* should only be used
without setting *norm*.

Effectless parameters of `.Figure.colorbar` and `matplotlib.colorbar.Colorbar`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The *cmap* and *norm* parameters of `.Figure.colorbar` and
`matplotlib.colorbar.Colorbar` have no effect because they are always
overridden by the mappable's colormap and norm; they are thus deprecated.
Likewise, passing the *alpha*, *boundaries*, *values*, *extend*, or *filled*
parameters with a `.ContourSet` mappable, or the *alpha* parameter with an
`.Artist` mappable, is deprecated, as the mappable would likewise override
them.
4 changes: 2 additions & 2 deletions examples/images_contours_and_fields/contour_demo.py
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Expand Up @@ -82,7 +82,7 @@
im = ax.imshow(Z, interpolation='bilinear', origin='lower',
cmap=cm.gray, extent=(-3, 3, -2, 2))
levels = np.arange(-1.2, 1.6, 0.2)
CS = ax.contour(Z, levels, origin='lower', cmap='flag',
CS = ax.contour(Z, levels, origin='lower', cmap='flag', extend='both',
linewidths=2, extent=(-3, 3, -2, 2))

# Thicken the zero contour.
Expand All @@ -93,7 +93,7 @@
inline=1, fmt='%1.1f', fontsize=14)

# make a colorbar for the contour lines
CB = fig.colorbar(CS, shrink=0.8, extend='both')
CB = fig.colorbar(CS, shrink=0.8)

ax.set_title('Lines with colorbar')

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52 changes: 33 additions & 19 deletions lib/matplotlib/colorbar.py
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Expand Up @@ -1155,6 +1155,19 @@ def remove(self):
self.ax.remove()


def _add_disjoint_kwargs(d, **kwargs):
"""
Update dict *d* with entries in *kwargs*, which must be absent from *d*.
"""
for k, v in kwargs.items():
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Should get a docstring. In particular, it should mention that d is a dict and is updated with kwargs. Also, I'd rather use _add_disjoint_kwargs. "merge" sounds more like it would return a new dict with the merged content.

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sure, done

if k in d:
cbook.warn_deprecated(
"3.3", message=f"The {k!r} parameter to Colorbar has no "
"effect because it is overridden by the mappable; it is "
"deprecated since %(since)s and will be removed %(removal)s.")
d[k] = v


class Colorbar(ColorbarBase):
"""
This class connects a `ColorbarBase` to a `~.cm.ScalarMappable`
Expand All @@ -1165,35 +1178,36 @@ class Colorbar(ColorbarBase):
`.Figure.colorbar` or `.pyplot.colorbar` to create a colorbar.
"""

def __init__(self, ax, mappable, **kw):
def __init__(self, ax, mappable, **kwargs):
# Ensure the given mappable's norm has appropriate vmin and vmax set
# even if mappable.draw has not yet been called.
if mappable.get_array() is not None:
mappable.autoscale_None()

self.mappable = mappable
kw['cmap'] = cmap = mappable.cmap
kw['norm'] = mappable.norm
_add_disjoint_kwargs(kwargs, cmap=mappable.cmap, norm=mappable.norm)

if isinstance(mappable, contour.ContourSet):
CS = mappable
kw['alpha'] = mappable.get_alpha()
kw['boundaries'] = CS._levels
kw['values'] = CS.cvalues
kw['extend'] = CS.extend
kw.setdefault('ticks', ticker.FixedLocator(CS.levels, nbins=10))
kw['filled'] = CS.filled
ColorbarBase.__init__(self, ax, **kw)
if not CS.filled:
self.add_lines(CS)
cs = mappable
_add_disjoint_kwargs(
kwargs,
alpha=cs.get_alpha(),
boundaries=cs._levels,
values=cs.cvalues,
extend=cs.extend,
filled=cs.filled,
)
kwargs.setdefault(
'ticks', ticker.FixedLocator(cs.levels, nbins=10))
ColorbarBase.__init__(self, ax, **kwargs)
if not cs.filled:
self.add_lines(cs)
else:
if getattr(cmap, 'colorbar_extend', False) is not False:
kw.setdefault('extend', cmap.colorbar_extend)

if getattr(mappable.cmap, 'colorbar_extend', False) is not False:
kwargs.setdefault('extend', mappable.cmap.colorbar_extend)
if isinstance(mappable, martist.Artist):
kw['alpha'] = mappable.get_alpha()

ColorbarBase.__init__(self, ax, **kw)
_add_disjoint_kwargs(kwargs, alpha=mappable.get_alpha())
ColorbarBase.__init__(self, ax, **kwargs)

def on_mappable_changed(self, mappable):
"""
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8 changes: 3 additions & 5 deletions lib/matplotlib/tests/test_colorbar.py
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Expand Up @@ -243,8 +243,7 @@ def test_colorbar_closed_patch():
# because it is matched to the data range in the image and to
# the number of colors in the LUT.
values = np.linspace(0, 10, 5)
cbar_kw = dict(cmap=cmap, orientation='horizontal', values=values,
ticks=[])
cbar_kw = dict(orientation='horizontal', values=values, ticks=[])

# The wide line is to show that the closed path is being handled
# correctly. See PR #4186.
Expand All @@ -264,9 +263,8 @@ def test_colorbar_ticks():
Z = X * Y
clevs = np.array([-12, -5, 0, 5, 12], dtype=float)
colors = ['r', 'g', 'b', 'c']
cs = ax.contourf(X, Y, Z, clevs, colors=colors)
cbar = fig.colorbar(cs, ax=ax, extend='neither',
orientation='horizontal', ticks=clevs)
cs = ax.contourf(X, Y, Z, clevs, colors=colors, extend='neither')
cbar = fig.colorbar(cs, ax=ax, orientation='horizontal', ticks=clevs)
assert len(cbar.ax.xaxis.get_ticklocs()) == len(clevs)


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