Support for additional axis kwargs (#2294)

1. Support xscale, yscale, xticks, yticks, xlim, ylim kwargs.

2. Small fixes:
    1. Forgot to replace autofmt_xdate for 2D plots.
    2. Use matplotlib's axis inverting methods.
    3. Don't automatically set histogram ylabel to be 'count'.

Author: dcherian

doc/plotting.rst

@@ -212,8 +212,6 @@ If required, the automatic legend can be turned off using ``add_legend=False``.
 ``hue`` can be passed directly to :py:func:`xarray.plot` as `air.isel(lon=10, lat=[19,21,22]).plot(hue='lat')`.
 
 
-
-
 Dimension along y-axis
 ~~~~~~~~~~~~~~~~~~~~~~
 
@@ -224,8 +222,8 @@ It is also possible to make line plots such that the data are on the x-axis and
     @savefig plotting_example_xy_kwarg.png
     air.isel(time=10, lon=[10, 11]).plot(y='lat', hue='lon')
 
-Changing Axes Direction
------------------------
+Other axes kwargs
+-----------------
 
 The keyword arguments ``xincrease`` and ``yincrease`` let you control the axes direction.
 
@@ -234,6 +232,9 @@ The keyword arguments ``xincrease`` and ``yincrease`` let you control the axes d
     @savefig plotting_example_xincrease_yincrease_kwarg.png
     air.isel(time=10, lon=[10, 11]).plot.line(y='lat', hue='lon', xincrease=False, yincrease=False)
 
+In addition, one can use ``xscale, yscale`` to set axes scaling; ``xticks, yticks`` to set axes ticks and ``xlim, ylim`` to set axes limits. These accept the same values as the matplotlib methods ``Axes.set_(x,y)scale()``, ``Axes.set_(x,y)ticks()``, ``Axes.set_(x,y)lim()`` respectively.
+
+
 Two Dimensions
 --------------
 

doc/whats-new.rst

@@ -36,6 +36,9 @@ Documentation
 Enhancements
 ~~~~~~~~~~~~
 
+- :py:meth:`plot()` now accepts the kwargs ``xscale, yscale, xlim, ylim, xticks, yticks`` just like Pandas. Also ``xincrease=False, yincrease=False`` now use matplotlib's axis inverting methods instead of setting limits.
+  By `Deepak Cherian <https://github.com/dcherian>`_. (:issue:`2224`)
+
 - DataArray coordinates and Dataset coordinates and data variables are
   now displayed as `a b ... y z` rather than `a b c d ...`.
   (:issue:`1186`)

xarray/plot/plot.py

@@ -270,6 +270,10 @@ def line(darray, *args, **kwargs):
         Coordinates for x, y axis. Only one of these may be specified.
         The other coordinate plots values from the DataArray on which this
         plot method is called.
+    xscale, yscale : 'linear', 'symlog', 'log', 'logit', optional
+        Specifies scaling for the x- and y-axes respectively
+    xticks, yticks : Specify tick locations for x- and y-axes
+    xlim, ylim : Specify x- and y-axes limits
     xincrease : None, True, or False, optional
         Should the values on the x axes be increasing from left to right?
         if None, use the default for the matplotlib function.
@@ -305,8 +309,14 @@ def line(darray, *args, **kwargs):
     hue = kwargs.pop('hue', None)
     x = kwargs.pop('x', None)
     y = kwargs.pop('y', None)
-    xincrease = kwargs.pop('xincrease', True)
-    yincrease = kwargs.pop('yincrease', True)
+    xincrease = kwargs.pop('xincrease', None)  # default needs to be None
+    yincrease = kwargs.pop('yincrease', None)
+    xscale = kwargs.pop('xscale', None)  # default needs to be None
+    yscale = kwargs.pop('yscale', None)
+    xticks = kwargs.pop('xticks', None)
+    yticks = kwargs.pop('yticks', None)
+    xlim = kwargs.pop('xlim', None)
+    ylim = kwargs.pop('ylim', None)
     add_legend = kwargs.pop('add_legend', True)
     _labels = kwargs.pop('_labels', True)
     if args is ():
@@ -343,7 +353,8 @@ def line(darray, *args, **kwargs):
             xlabels.set_rotation(30)
             xlabels.set_ha('right')
 
-    _update_axes_limits(ax, xincrease, yincrease)
+    _update_axes(ax, xincrease, yincrease, xscale, yscale,
+                 xticks, yticks, xlim, ylim)
 
     return primitive
 
@@ -378,37 +389,69 @@ def hist(darray, figsize=None, size=None, aspect=None, ax=None, **kwargs):
     """
     ax = get_axis(figsize, size, aspect, ax)
 
+    xincrease = kwargs.pop('xincrease', None)  # default needs to be None
+    yincrease = kwargs.pop('yincrease', None)
+    xscale = kwargs.pop('xscale', None)  # default needs to be None
+    yscale = kwargs.pop('yscale', None)
+    xticks = kwargs.pop('xticks', None)
+    yticks = kwargs.pop('yticks', None)
+    xlim = kwargs.pop('xlim', None)
+    ylim = kwargs.pop('ylim', None)
+
     no_nan = np.ravel(darray.values)
     no_nan = no_nan[pd.notnull(no_nan)]
 
     primitive = ax.hist(no_nan, **kwargs)
 
-    ax.set_ylabel('Count')
-
     ax.set_title('Histogram')
     ax.set_xlabel(label_from_attrs(darray))
 
+    _update_axes(ax, xincrease, yincrease, xscale, yscale,
+                 xticks, yticks, xlim, ylim)
+
     return primitive
 
 
-def _update_axes_limits(ax, xincrease, yincrease):
+def _update_axes(ax, xincrease, yincrease,
+                 xscale=None, yscale=None,
+                 xticks=None, yticks=None,
+                 xlim=None, ylim=None):
     """
-    Update axes in place to increase or decrease
-    For use in _plot2d
+    Update axes with provided parameters
     """
     if xincrease is None:
         pass
-    elif xincrease:
-        ax.set_xlim(sorted(ax.get_xlim()))
-    elif not xincrease:
-        ax.set_xlim(sorted(ax.get_xlim(), reverse=True))
+    elif xincrease and ax.xaxis_inverted():
+        ax.invert_xaxis()
+    elif not xincrease and not ax.xaxis_inverted():
+        ax.invert_xaxis()
 
     if yincrease is None:
         pass
-    elif yincrease:
-        ax.set_ylim(sorted(ax.get_ylim()))
-    elif not yincrease:
-        ax.set_ylim(sorted(ax.get_ylim(), reverse=True))
+    elif yincrease and ax.yaxis_inverted():
+        ax.invert_yaxis()
+    elif not yincrease and not ax.yaxis_inverted():
+        ax.invert_yaxis()
+
+    # The default xscale, yscale needs to be None.
+    # If we set a scale it resets the axes formatters,
+    # This means that set_xscale('linear') on a datetime axis
+    # will remove the date labels. So only set the scale when explicitly
+    # asked to. https://github.com/matplotlib/matplotlib/issues/8740
+    if xscale is not None:
+        ax.set_xscale(xscale)
+    if yscale is not None:
+        ax.set_yscale(yscale)
+
+    if xticks is not None:
+        ax.set_xticks(xticks)
+    if yticks is not None:
+        ax.set_yticks(yticks)
+
+    if xlim is not None:
+        ax.set_xlim(xlim)
+    if ylim is not None:
+        ax.set_ylim(ylim)
 
 
 # MUST run before any 2d plotting functions are defined since
@@ -500,6 +543,10 @@ def _plot2d(plotfunc):
         If passed, make column faceted plots on this dimension name
     col_wrap : integer, optional
         Use together with ``col`` to wrap faceted plots
+    xscale, yscale : 'linear', 'symlog', 'log', 'logit', optional
+        Specifies scaling for the x- and y-axes respectively
+    xticks, yticks : Specify tick locations for x- and y-axes
+    xlim, ylim : Specify x- and y-axes limits
     xincrease : None, True, or False, optional
         Should the values on the x axes be increasing from left to right?
         if None, use the default for the matplotlib function.
@@ -577,7 +624,8 @@ def newplotfunc(darray, x=None, y=None, figsize=None, size=None,
                     cmap=None, center=None, robust=False, extend=None,
                     levels=None, infer_intervals=None, colors=None,
                     subplot_kws=None, cbar_ax=None, cbar_kwargs=None,
-                    **kwargs):
+                    xscale=None, yscale=None, xticks=None, yticks=None,
+                    xlim=None, ylim=None, **kwargs):
         # All 2d plots in xarray share this function signature.
         # Method signature below should be consistent.
 
@@ -723,11 +771,17 @@ def newplotfunc(darray, x=None, y=None, figsize=None, size=None,
             raise ValueError("cbar_ax and cbar_kwargs can't be used with "
                              "add_colorbar=False.")
 
-        _update_axes_limits(ax, xincrease, yincrease)
+        _update_axes(ax, xincrease, yincrease, xscale, yscale,
+                     xticks, yticks, xlim, ylim)
 
         # Rotate dates on xlabels
+        # Do this without calling autofmt_xdate so that x-axes ticks
+        # on other subplots (if any) are not deleted.
+        # https://stackoverflow.com/questions/17430105/autofmt-xdate-deletes-x-axis-labels-of-all-subplots
         if np.issubdtype(xval.dtype, np.datetime64):
-            ax.get_figure().autofmt_xdate()
+            for xlabels in ax.get_xticklabels():
+                xlabels.set_rotation(30)
+                xlabels.set_ha('right')
 
         return primitive
 
@@ -739,7 +793,9 @@ def plotmethod(_PlotMethods_obj, x=None, y=None, figsize=None, size=None,
                    add_labels=True, vmin=None, vmax=None, cmap=None,
                    colors=None, center=None, robust=False, extend=None,
                    levels=None, infer_intervals=None, subplot_kws=None,
-                   cbar_ax=None, cbar_kwargs=None, **kwargs):
+                   cbar_ax=None, cbar_kwargs=None,
+                   xscale=None, yscale=None, xticks=None, yticks=None,
+                   xlim=None, ylim=None, **kwargs):
         """
         The method should have the same signature as the function.
 

xarray/tests/test_plot.py

@@ -426,10 +426,6 @@ def test_xlabel_uses_name(self):
         self.darray.plot.hist()
         assert 'testpoints [testunits]' == plt.gca().get_xlabel()
 
-    def test_ylabel_is_count(self):
-        self.darray.plot.hist()
-        assert 'Count' == plt.gca().get_ylabel()
-
     def test_title_is_histogram(self):
         self.darray.plot.hist()
         assert 'Histogram' == plt.gca().get_title()
@@ -1675,3 +1671,68 @@ def test_plot_cftime_data_error():
     data = DataArray(data, coords=[np.arange(5)], dims=['x'])
     with raises_regex(NotImplementedError, 'cftime.datetime'):
         data.plot()
+
+
+test_da_list = [DataArray(easy_array((10, ))),
+                DataArray(easy_array((10, 3))),
+                DataArray(easy_array((10, 3, 2)))]
+
+
+@requires_matplotlib
+class TestAxesKwargs(object):
+    @pytest.mark.parametrize('da', test_da_list)
+    @pytest.mark.parametrize('xincrease', [True, False])
+    def test_xincrease_kwarg(self, da, xincrease):
+        plt.clf()
+        da.plot(xincrease=xincrease)
+        assert plt.gca().xaxis_inverted() == (not xincrease)
+
+    @pytest.mark.parametrize('da', test_da_list)
+    @pytest.mark.parametrize('yincrease', [True, False])
+    def test_yincrease_kwarg(self, da, yincrease):
+        plt.clf()
+        da.plot(yincrease=yincrease)
+        assert plt.gca().yaxis_inverted() == (not yincrease)
+
+    @pytest.mark.parametrize('da', test_da_list)
+    @pytest.mark.parametrize('xscale', ['linear', 'log', 'logit', 'symlog'])
+    def test_xscale_kwarg(self, da, xscale):
+        plt.clf()
+        da.plot(xscale=xscale)
+        assert plt.gca().get_xscale() == xscale
+
+    @pytest.mark.parametrize('da', [DataArray(easy_array((10, ))),
+                                    DataArray(easy_array((10, 3)))])
+    @pytest.mark.parametrize('yscale', ['linear', 'log', 'logit', 'symlog'])
+    def test_yscale_kwarg(self, da, yscale):
+        plt.clf()
+        da.plot(yscale=yscale)
+        assert plt.gca().get_yscale() == yscale
+
+    @pytest.mark.parametrize('da', test_da_list)
+    def test_xlim_kwarg(self, da):
+        plt.clf()
+        expected = (0.0, 1000.0)
+        da.plot(xlim=[0, 1000])
+        assert plt.gca().get_xlim() == expected
+
+    @pytest.mark.parametrize('da', test_da_list)
+    def test_ylim_kwarg(self, da):
+        plt.clf()
+        da.plot(ylim=[0, 1000])
+        expected = (0.0, 1000.0)
+        assert plt.gca().get_ylim() == expected
+
+    @pytest.mark.parametrize('da', test_da_list)
+    def test_xticks_kwarg(self, da):
+        plt.clf()
+        da.plot(xticks=np.arange(5))
+        expected = np.arange(5).tolist()
+        assert np.all(plt.gca().get_xticks() == expected)
+
+    @pytest.mark.parametrize('da', test_da_list)
+    def test_yticks_kwarg(self, da):
+        plt.clf()
+        da.plot(yticks=np.arange(5))
+        expected = np.arange(5)
+        assert np.all(plt.gca().get_yticks() == expected)