plot.imshow now obeys 'origin' kwarg.

doc/whats-new.rst

@@ -71,6 +71,10 @@ Enhancements
 Bug fixes
 ~~~~~~~~~
 
+- ``xarray.plot.imshow()`` correctly uses the ``origin`` argument.
+  (:issue:`2379`)
+  By `Deepak Cherian <https://github.com/dcherian>`_.
+
 - Fixed ``DataArray.to_iris()`` failure while creating ``DimCoord`` by
   falling back to creating ``AuxCoord``. Fixed dependency on ``var_name``
   attribute being set.

xarray/plot/plot.py

@@ -619,7 +619,7 @@ def _plot2d(plotfunc):
     @functools.wraps(plotfunc)
     def newplotfunc(darray, x=None, y=None, figsize=None, size=None,
                     aspect=None, ax=None, row=None, col=None,
-                    col_wrap=None, xincrease=True, yincrease=True,
+                    col_wrap=None, xincrease=None, yincrease=None,
                     add_colorbar=None, add_labels=True, vmin=None, vmax=None,
                     cmap=None, center=None, robust=False, extend=None,
                     levels=None, infer_intervals=None, colors=None,
@@ -789,7 +789,7 @@ def newplotfunc(darray, x=None, y=None, figsize=None, size=None,
     @functools.wraps(newplotfunc)
     def plotmethod(_PlotMethods_obj, x=None, y=None, figsize=None, size=None,
                    aspect=None, ax=None, row=None, col=None, col_wrap=None,
-                   xincrease=True, yincrease=True, add_colorbar=None,
+                   xincrease=None, yincrease=None, add_colorbar=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,
@@ -857,10 +857,8 @@ def imshow(x, y, z, ax, **kwargs):
     left, right = x[0] - xstep, x[-1] + xstep
     bottom, top = y[-1] + ystep, y[0] - ystep
 
-    defaults = {'extent': [left, right, bottom, top],
-                'origin': 'upper',
-                'interpolation': 'nearest',
-                }
+    defaults = {'origin': 'upper',
+                'interpolation': 'nearest'}
 
     if not hasattr(ax, 'projection'):
         # not for cartopy geoaxes
@@ -869,6 +867,11 @@ def imshow(x, y, z, ax, **kwargs):
     # Allow user to override these defaults
     defaults.update(kwargs)
 
+    if defaults['origin'] == 'upper':
+        defaults['extent'] = [left, right, bottom, top]
+    else:
+        defaults['extent'] = [left, right, top, bottom]
+
     if z.ndim == 3:
         # matplotlib imshow uses black for missing data, but Xarray makes
         # missing data transparent.  We therefore add an alpha channel if

xarray/tests/test_plot.py

@@ -1284,6 +1284,17 @@ def test_regression_rgb_imshow_dim_size_one(self):
         da = DataArray(easy_array((1, 3, 3), start=0.0, stop=1.0))
         da.plot.imshow()
 
+    def test_imshow_origin_kwarg(self):
+        da = DataArray(easy_array((5, 5, 3), start=-0.6, stop=1.4))
+        da.plot.imshow(origin='upper')
+        assert plt.xlim()[0] < 0
+        assert plt.ylim()[1] < 0
+
+        plt.clf()
+        da.plot.imshow(origin='lower')
+        assert plt.xlim()[0] < 0
+        assert plt.ylim()[0] < 0
+
 
 class TestFacetGrid(PlotTestCase):
     def setUp(self):