WIP DataArray.plot() can now plot errorbars with kwargs xerr, yerr

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
 ~~~~~~~~~~~~~~~~~~~~~~
 
@@ -225,7 +223,7 @@ It is also possible to make line plots such that the data are on the x-axis and
     air.isel(time=10, lon=[10, 11]).plot(y='lat', hue='lon')
 
 Changing Axes Direction
------------------------
+~~~~~~~~~~~~~~~~~~~~~~~
 
 The keyword arguments ``xincrease`` and ``yincrease`` let you control the axes direction.
 
@@ -234,6 +232,16 @@ 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)
 
+Errorbars
+~~~~~~~~~
+
+If provided with the keyword arguments ``xerr`` and ``yerr``, errorbars will be added. Additional ``kwargs`` will be passed to matplotlib's ``errorbar()``. Currently this functionality is only supported for 1D DataArrays; i.e. the following would not work with ``air.isel(time=10, lon=[10, 11])``.
+
+.. ipython:: python
+
+    @savefig plotting_example_yerr_kwarg.png
+    air.isel(time=10, lon=10).plot.line(y='lat', xerr=3, yerr=1.5, ecolor='r')
+
 Two Dimensions
 --------------
 

doc/whats-new.rst

@@ -41,6 +41,9 @@ Enhancements
   (:issue:`2218`)
   By `Keisuke Fujii <https://github.com/fujiisoup>`_.
 
+- :py:meth:`~xarray.DataArray.plot()` will now plot errorbars if provided with kwargs ``xerr, yerr``.
+  By `Deepak Cherian <https://github.com/dcherian>`_.
+
 
 Bug fixes
 ~~~~~~~~~

xarray/plot/plot.py

@@ -270,6 +270,7 @@ 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.
+    xerr, yerr : Errorbar sizes (optional)
     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.
@@ -308,6 +309,8 @@ def line(darray, *args, **kwargs):
     y = kwargs.pop('y', None)
     xincrease = kwargs.pop('xincrease', True)
     yincrease = kwargs.pop('yincrease', True)
+    xerr = kwargs.pop('xerr', None)
+    yerr = kwargs.pop('yerr', None)
     add_legend = kwargs.pop('add_legend', True)
     _labels = kwargs.pop('_labels', True)
 
@@ -317,7 +320,13 @@ def line(darray, *args, **kwargs):
 
     _ensure_plottable(xplt)
 
-    primitive = ax.plot(xplt, yplt, *args, **kwargs)
+    if xerr is None and yerr is None:
+        primitive = ax.plot(xplt, yplt, *args, **kwargs)
+    else:
+        if xplt.ndim > 1 or yplt.ndim > 1:
+            raise ValueError('xerr, yerr can only be used with 1D data.')
+
+        primitive = ax.errorbar(xplt, yplt, xerr=xerr, yerr=yerr, **kwargs)
 
     if _labels:
         if xlabel is not None:

xarray/tests/test_plot.py

@@ -148,6 +148,9 @@ def test_2d_line(self):
         self.darray[:, :, 0].plot.line(x='dim_0', hue='dim_1')
         self.darray[:, :, 0].plot.line(y='dim_0', hue='dim_1')
 
+        with raises_regex(ValueError, 'xerr, yerr'):
+            self.darray[:, :, 0].plot.line(y='dim_0', hue='dim_1', xerr=1)
+
         with raises_regex(ValueError, 'cannot'):
             self.darray[:, :, 0].plot.line(x='dim_1', y='dim_0', hue='dim_1')
 
@@ -391,6 +394,12 @@ def test_slice_in_title(self):
         title = plt.gca().get_title()
         assert 'd = 10' == title
 
+    def test_errorbars(self):
+        primitive = self.darray.plot(xerr=self.darray / 2,
+                                     yerr=self.darray / 2,
+                                     ecolor='r')
+        assert isinstance(primitive, mpl.container.ErrorbarContainer)
+
 
 class TestPlotHistogram(PlotTestCase):
     def setUp(self):