pcolormesh is default 2d plotting method and updates to plotting docs

Author: Joe Hamman

doc/plotting.rst

@@ -141,8 +141,7 @@ Simple Example
 ~~~~~~~~~~~~~~
 
 The default method :py:meth:`xray.DataArray.plot` sees that the data is
-2 dimensional. If the coordinates are uniformly spaced then it
-calls :py:func:`xray.plot.imshow`.
+2 dimensional and calls :py:func:`xray.plot.pcolormesh`.
 
 .. ipython:: python
 
@@ -176,9 +175,9 @@ Xray plots data with :ref:`missing_values`.
 Nonuniform Coordinates
 ~~~~~~~~~~~~~~~~~~~~~~
 
-It's not necessary for the coordinates to be evenly spaced. If not, then
-:py:meth:`xray.DataArray.plot` produces a filled contour plot by calling
-:py:func:`xray.plot.contourf`.
+It's not necessary for the coordinates to be evenly spaced. Both
+:py:func:`xray.plot.pcolormesh` (default) and :py:func:`xray.plot.contourf` can
+produce plots with nonuniform coordinates.
 
 .. ipython:: python
 
@@ -201,6 +200,7 @@ matplotlib is available.
     plt.title('These colors prove North America\nhas fallen in the ocean')
     plt.ylabel('latitude')
     plt.xlabel('longitude')
+    plt.tight_layout()
 
     @savefig plotting_2d_call_matplotlib.png width=4in
     plt.show()
@@ -376,8 +376,8 @@ Faceted plotting supports other arguments common to xray 2d plots.
     hasoutliers[-1, -1, -1] = 400
 
     @savefig plot_facet_robust.png height=12in
-    g = hasoutliers.plot.imshow('lon', 'lat', col='time', col_wrap=3,
-                                robust=True, cmap='viridis')
+    g = hasoutliers.plot.pcolormesh('lon', 'lat', col='time', col_wrap=3,
+                                    robust=True, cmap='viridis')
 
 FacetGrid Objects
 ~~~~~~~~~~~~~~~~~
@@ -473,14 +473,13 @@ plotting function based on the dimensions of the ``DataArray`` and whether
 the coordinates are sorted and uniformly spaced. This table
 describes what gets plotted:
 
-=============== =========== ===========================
-Dimensions      Coordinates Plotting function
---------------- ----------- ---------------------------
-1                           :py:func:`xray.plot.line`
-2               Uniform     :py:func:`xray.plot.imshow`
-2               Irregular   :py:func:`xray.plot.contourf`
-Anything else               :py:func:`xray.plot.hist`
-=============== =========== ===========================
+=============== ===========================
+Dimensions      Plotting function
+--------------- ---------------------------
+1               :py:func:`xray.plot.line`
+2               :py:func:`xray.plot.pcolormesh`
+Anything else   :py:func:`xray.plot.hist`
+=============== ===========================
 
 Coordinates
 ~~~~~~~~~~~

xray/plot/facetgrid.py

@@ -274,7 +274,7 @@ def map_dataarray(self, func, x, y, **kwargs):
                                      extend=cmap_params['extend'])
 
             if self.data.name:
-                cbar.set_label(self.data.name, rotation=270,
+                cbar.set_label(self.data.name, rotation=90,
                                verticalalignment='bottom')
 
         self._x_var = x

xray/plot/plot.py

@@ -15,7 +15,6 @@
 
 from .utils import _determine_cmap_params, _infer_xy_labels
 from .facetgrid import FacetGrid
-from ..core.utils import is_uniform_spaced
 
 
 # Maybe more appropriate to keep this in .utils
@@ -58,19 +57,18 @@ def _easy_facetgrid(darray, plotfunc, x, y, row=None, col=None, col_wrap=None,
 def plot(darray, row=None, col=None, col_wrap=None, ax=None, rtol=0.01,
          subplot_kws=None, **kwargs):
     """
-    Default plot of DataArray using matplotlib / pylab.
+    Default plot of DataArray using matplotlib.pyplot.
 
     Calls xray plotting function based on the dimensions of
     darray.squeeze()
 
-    =============== =========== ===========================
-    Dimensions      Coordinates Plotting function
-    --------------- ----------- ---------------------------
-    1                           :py:func:`xray.plot.line`
-    2               Uniform     :py:func:`xray.plot.imshow`
-    2               Irregular   :py:func:`xray.plot.contourf`
-    Anything else               :py:func:`xray.plot.hist`
-    =============== =========== ===========================
+    =============== ===========================
+    Dimensions      Plotting function
+    --------------- ---------------------------
+    1               :py:func:`xray.plot.line`
+    2               :py:func:`xray.plot.pcolormesh`
+    Anything else   :py:func:`xray.plot.hist`
+    =============== ===========================
 
     Parameters
     ----------
@@ -115,9 +113,7 @@ def plot(darray, row=None, col=None, col_wrap=None, ax=None, rtol=0.01,
         kwargs['col_wrap'] = col_wrap
         kwargs['subplot_kws'] = subplot_kws
 
-        indexes = (darray.indexes[dim].values for dim in plot_dims)
-        uniform = all(is_uniform_spaced(i, rtol=rtol) for i in indexes)
-        plotfunc = imshow if uniform else contourf
+        plotfunc = pcolormesh
     else:
         if row or col:
             raise ValueError(error_msg)
@@ -335,7 +331,7 @@ def _plot2d(plotfunc):
 
     @functools.wraps(plotfunc)
     def newplotfunc(darray, x=None, y=None, ax=None, row=None, col=None,
-                    col_wrap=None, xincrease=None, yincrease=None,
+                    col_wrap=None, xincrease=True, yincrease=True,
                     add_colorbar=True, add_labels=True, vmin=None, vmax=None,
                     cmap=None, center=None, robust=False, extend=None,
                     levels=None, colors=None, subplot_kws=None, **kwargs):
@@ -429,7 +425,7 @@ def newplotfunc(darray, x=None, y=None, ax=None, row=None, col=None,
         if add_colorbar:
             cbar = plt.colorbar(primitive, ax=ax, extend=cmap_params['extend'])
             if darray.name and add_labels:
-                cbar.set_label(darray.name)
+                cbar.set_label(darray.name, rotation=90)
 
         _update_axes_limits(ax, xincrease, yincrease)
 
@@ -438,7 +434,7 @@ def newplotfunc(darray, x=None, y=None, ax=None, row=None, col=None,
     # For use as DataArray.plot.plotmethod
     @functools.wraps(newplotfunc)
     def plotmethod(_PlotMethods_obj, x=None, y=None, ax=None, row=None,
-                   col=None, col_wrap=None, xincrease=None, yincrease=None,
+                   col=None, col_wrap=None, xincrease=True, yincrease=True,
                    add_colorbar=True, add_labels=True, vmin=None, vmax=None,
                    cmap=None, colors=None, center=None, robust=False,
                    extend=None, levels=None, subplot_kws=None, **kwargs):
@@ -464,7 +460,7 @@ def plotmethod(_PlotMethods_obj, x=None, y=None, ax=None, row=None,
 @_plot2d
 def imshow(x, y, z, ax, **kwargs):
     """
-    Image plot of 2d DataArray using matplotlib / pylab
+    Image plot of 2d DataArray using matplotlib.pyplot
 
     Wraps matplotlib.pyplot.imshow
 
@@ -478,7 +474,7 @@ def imshow(x, y, z, ax, **kwargs):
     """
 
     if x.ndim != 1 or y.ndim != 1:
-        raise ValueError('Imshow requires 1D coordinates, try using '
+        raise ValueError('imshow requires 1D coordinates, try using '
                          'pcolormesh or contour(f)')
 
     # Centering the pixels- Assumes uniform spacing

xray/test/test_plot.py

@@ -89,12 +89,12 @@ def test_2d_before_squeeze(self):
         a.plot()
 
     def test2d_uniform_calls_imshow(self):
-        self.assertTrue(self.imshow_called(self.darray[:, :, 0].plot))
+        self.assertTrue(self.imshow_called(self.darray[:, :, 0].plot.imshow))
 
     def test2d_nonuniform_calls_contourf(self):
         a = self.darray[:, :, 0]
         a.coords['dim_1'] = [2, 1, 89]
-        self.assertTrue(self.contourf_called(a.plot))
+        self.assertTrue(self.contourf_called(a.plot.contourf))
 
     def test3d(self):
         self.darray.plot()
@@ -707,7 +707,7 @@ def test_imshow_called(self):
         self.assertTrue(self.imshow_called(self.darray.plot.imshow))
 
     def test_xy_pixel_centered(self):
-        self.darray.plot.imshow()
+        self.darray.plot.imshow(yincrease=None)
         self.assertTrue(np.allclose([-0.5, 14.5], plt.gca().get_xlim()))
         self.assertTrue(np.allclose([9.5, -0.5], plt.gca().get_ylim()))