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BUG: contour plot levels #868

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Merged
merged 7 commits into from
Jul 20, 2016
Merged

BUG: contour plot levels #868

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f38bfc5
fix: contour plot levels
fmaussion Jun 3, 2016
a4bafee
cleaned up tests
fmaussion Jun 9, 2016
2b48428
cbar defaults to None
fmaussion Jul 20, 2016
e45d6e5
Merge remote-tracking branch 'upstream/master' into contour
fmaussion Jul 20, 2016
400fd74
whats new
fmaussion Jul 20, 2016
cd624ee
forgot something
fmaussion Jul 20, 2016
ff721b6
forgot something again
fmaussion Jul 20, 2016
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4 changes: 4 additions & 0 deletions doc/whats-new.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@ Breaking changes
- Indexing on multi-index now drop levels, which is consitent with pandas.
It also changes the name of the dimension / coordinate when the multi-index is
reduced to a single index.
- Contour plots no longer add a colorbar per default (:issue:`866`).

Enhancements
~~~~~~~~~~~~
Expand Down Expand Up @@ -100,6 +101,9 @@ Bug fixes
- Fixed incorrect test for dask version :issue:`891`. By
`Stephan Hoyer <https://github.com/shoyer>`_.

- :py:func:`~xarray.plot.contour` now plots the correct number of contours
(:issue:`866`). By `Fabien Maussion <https://github.com/fmaussion>`_.

.. _whats-new.0.7.2:

v0.7.2 (13 March 2016)
Expand Down
8 changes: 6 additions & 2 deletions xarray/plot/plot.py
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Original file line number Diff line number Diff line change
Expand Up @@ -339,13 +339,17 @@ def _plot2d(plotfunc):
@functools.wraps(plotfunc)
def newplotfunc(darray, x=None, y=None, ax=None, row=None, col=None,
col_wrap=None, xincrease=True, yincrease=True,
add_colorbar=True, add_labels=True, vmin=None, vmax=None,
add_colorbar=None, add_labels=True, vmin=None, vmax=None,
cmap=None, center=None, robust=False, extend=None,
levels=None, colors=None, subplot_kws=None,
cbar_ax=None, cbar_kwargs=None, **kwargs):
# All 2d plots in xarray share this function signature.
# Method signature below should be consistent.

# Decide on a default for the colorbar before facetgrids
if add_colorbar is None:
add_colorbar = plotfunc.__name__ != 'contour'

# Handle facetgrids first
if row or col:
allargs = locals().copy()
Expand Down Expand Up @@ -450,7 +454,7 @@ def newplotfunc(darray, x=None, y=None, ax=None, row=None, col=None,
@functools.wraps(newplotfunc)
def plotmethod(_PlotMethods_obj, x=None, y=None, ax=None, row=None,
col=None, col_wrap=None, xincrease=True, yincrease=True,
add_colorbar=True, add_labels=True, vmin=None, vmax=None,
add_colorbar=None, add_labels=True, vmin=None, vmax=None,
cmap=None, colors=None, center=None, robust=False,
extend=None, levels=None, subplot_kws=None,
cbar_ax=None, cbar_kwargs=None, **kwargs):
Expand Down
2 changes: 1 addition & 1 deletion xarray/plot/utils.py
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Expand Up @@ -41,7 +41,7 @@ def _build_discrete_cmap(cmap, levels, extend, filled):

if not filled:
# non-filled contour plots
extend = 'neither'
extend = 'max'
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I think I missed the rationale for this one -- why should this change?

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This is the actual bug fix for #866 which motivated this PR ;-).

xarray wasn't plotting contours correctly before this change, see the following code:

import numpy as np
import matplotlib.pyplot as plt
import xarray as xr

x, y = np.meshgrid(np.arange(12), np.arange(12))
z = xr.DataArray(np.sqrt(x**2 + y**2))
z.plot.contour(levels=[2, 4, 6, 8], add_colorbar=False, colors='k')
plt.show()

figure_1

With this fix everything is fine now:

figure_1-1

Intuitively, it also makes sense: the last contour does mark all data beyond the last level, hence extend = 'max'

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Got it, thanks!


if extend == 'both':
ext_n = 2
Expand Down
37 changes: 29 additions & 8 deletions xarray/test/test_plot.py
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Expand Up @@ -414,7 +414,7 @@ def test_build_discrete_cmap(self):
if filled:
self.assertEqual(ncmap.colorbar_extend, extend)
else:
self.assertEqual(ncmap.colorbar_extend, 'neither')
self.assertEqual(ncmap.colorbar_extend, 'max')

def test_discrete_colormap_list_of_levels(self):
for extend, levels in [('max', [-1, 2, 4, 8, 10]),
Expand All @@ -429,7 +429,7 @@ def test_discrete_colormap_list_of_levels(self):
if kind != 'contour':
self.assertEqual(extend, primitive.cmap.colorbar_extend)
else:
self.assertEqual('neither', primitive.cmap.colorbar_extend)
self.assertEqual('max', primitive.cmap.colorbar_extend)
self.assertEqual(len(levels) - 1, len(primitive.cmap.colors))

def test_discrete_colormap_int_levels(self):
Expand All @@ -454,7 +454,7 @@ def test_discrete_colormap_int_levels(self):
if kind != 'contour':
self.assertEqual(extend, primitive.cmap.colorbar_extend)
else:
self.assertEqual('neither', primitive.cmap.colorbar_extend)
self.assertEqual('max', primitive.cmap.colorbar_extend)
self.assertGreaterEqual(levels, len(primitive.cmap.colors))

def test_discrete_colormap_list_levels_and_vmin_or_vmax(self):
Expand Down Expand Up @@ -620,7 +620,7 @@ def test_default_title(self):

def test_colorbar_default_label(self):
self.darray.name = 'testvar'
self.plotmethod()
self.plotmethod(add_colorbar=True)
self.assertIn(self.darray.name, text_in_fig())

def test_no_labels(self):
Expand All @@ -633,26 +633,28 @@ def test_no_labels(self):
def test_colorbar_kwargs(self):
# replace label
self.darray.name = 'testvar'
self.plotmethod(cbar_kwargs={'label':'MyLabel'})
self.plotmethod(add_colorbar=True, cbar_kwargs={'label':'MyLabel'})
alltxt = text_in_fig()
self.assertIn('MyLabel', alltxt)
self.assertNotIn('testvar', alltxt)
# you can use mapping types as well
self.plotmethod(cbar_kwargs=(('label', 'MyLabel'),))
self.plotmethod(add_colorbar=True, cbar_kwargs=(('label', 'MyLabel'),))
alltxt = text_in_fig()
self.assertIn('MyLabel', alltxt)
self.assertNotIn('testvar', alltxt)
# change cbar ax
fig, (ax, cax) = plt.subplots(1, 2)
self.plotmethod(ax=ax, cbar_ax=cax, cbar_kwargs={'label':'MyBar'})
self.plotmethod(ax=ax, cbar_ax=cax, add_colorbar=True,
cbar_kwargs={'label':'MyBar'})
self.assertTrue(ax.has_data())
self.assertTrue(cax.has_data())
alltxt = text_in_fig()
self.assertIn('MyBar', alltxt)
self.assertNotIn('testvar', alltxt)
# note that there are two ways to achieve this
fig, (ax, cax) = plt.subplots(1, 2)
self.plotmethod(ax=ax, cbar_kwargs={'label':'MyBar', 'cax':cax})
self.plotmethod(ax=ax, add_colorbar=True,
cbar_kwargs={'label':'MyBar', 'cax':cax})
self.assertTrue(ax.has_data())
self.assertTrue(cax.has_data())
alltxt = text_in_fig()
Expand Down Expand Up @@ -795,6 +797,19 @@ def _color_as_tuple(c):
_color_as_tuple(artist.cmap.colors[1]),
(0.0, 0.0, 1.0))

artist = self.darray.plot.contour(levels=[-0.5, 0., 0.5, 1.],
colors=['k', 'r', 'w', 'b'])
self.assertEqual(
_color_as_tuple(artist.cmap.colors[1]),
(1.0, 0.0, 0.0))
self.assertEqual(
_color_as_tuple(artist.cmap.colors[2]),
(1.0, 1.0, 1.0))
# the last color is now under "over"
self.assertEqual(
_color_as_tuple(artist.cmap._rgba_over),
(0.0, 0.0, 1.0))

def test_cmap_and_color_both(self):
with self.assertRaises(ValueError):
self.plotmethod(colors='k', cmap='RdBu')
Expand All @@ -810,6 +825,12 @@ def test_2d_coord_names(self):
self.assertEqual('x2d', ax.get_xlabel())
self.assertEqual('y2d', ax.get_ylabel())

def test_single_level(self):
# this used to raise an error, but not anymore since
# add_colorbar defaults to false
self.plotmethod(levels=[0.1])
self.plotmethod(levels=1)


class TestPcolormesh(Common2dMixin, PlotTestCase):

Expand Down