Added the ability for plot to put the cube data on the x axis if plotting just a cube against a vertical or y coordinate.

docs/iris/src/whatsnew/contributions_2.1/newfeature_2018-Feb-14_cube_plot_with_vertical.txt

@@ -0,0 +1 @@
+* iris.plot.plot an iris.quickplot.plot now automatically place the cube on the x axis if the primary coordinate being plotted against is a vertical coordinate. (e.g. ``iris.plot.plot(z_cube)`` would produce an z vs phenomenon plot, where before it would have produced a phenomenon vs z one)

lib/iris/plot.py

@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2010 - 2017, Met Office
+# (C) British Crown Copyright 2010 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -483,7 +483,19 @@ def _get_plot_objects(args):
         # single argument
         v_object = args[0]
         u_object = _u_object_from_v_object(v_object)
+
         u, v = _uv_from_u_object_v_object(u_object, args[0])
+
+        # If a single cube argument, and the associated dimension coordinate
+        # is vertical-like, put the coordinate on the y axis, and the data o
+        # the x.
+        if (isinstance(v_object, iris.cube.Cube) and
+                iris.util.guess_coord_axis(u_object) in ['Y', 'Z']):
+            # If we have a single argument, and it is vertial-like, put it on
+            # the y axis.
+            u_object, v_object = v_object, u_object
+            u, v = v, u
+
         args = args[1:]
     return u_object, v_object, u, v, args
 

lib/iris/quickplot.py

@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2010 - 2016, Met Office
+# (C) British Crown Copyright 2010 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -127,11 +127,8 @@ def _get_titles(u_object, v_object):
 
 
 def _label_1d_plot(*args):
-    if len(args) > 1 and isinstance(args[1],
-                                    (iris.cube.Cube, iris.coords.Coord)):
-        xlabel, ylabel, title = _get_titles(*args[:2])
-    else:
-        xlabel, ylabel, title = _get_titles(None, args[0])
+    u_obj, v_obj, _, _, _ = iplt._get_plot_objects(args)
+    xlabel, ylabel, title = _get_titles(u_obj, v_obj)
     plt.title(title)
     plt.xlabel(xlabel)
     plt.ylabel(ylabel)

lib/iris/tests/idiff.py

@@ -244,7 +244,7 @@ def step_over_diffs(result_dir, action, display=True):
                     if isinstance(e,  ValueError) or \
                             isinstance(e, ImageComparisonFailure):
                         print('Could not compare {}: {}'.format(result_fname,
-                                                                e.message))
+                                                                str(e)))
                         continue
                     else:
                         # Propagate the exception, keeping the stack trace

lib/iris/tests/unit/quickplot/test_plot.py

@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2014 - 2015, Met Office
+# (C) British Crown Copyright 2014 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -22,6 +22,7 @@
 # Import iris.tests first so that some things can be initialised before
 # importing anything else.
 import iris.tests as tests
+from iris.tests.stock import simple_2d
 from iris.tests.unit.plot import TestGraphicStringCoord
 
 if tests.MPL_AVAILABLE:
@@ -43,5 +44,28 @@ def test_xaxis_labels(self):
         self.assertPointsTickLabels('xaxis')
 
 
+class TestAxisLabels(tests.GraphicsTest):
+    def test_xy_cube(self):
+        c = simple_2d()[:, 0]
+        qplt.plot(c)
+        ax = qplt.plt.gca()
+        x = ax.xaxis.get_label().get_text()
+        self.assertEqual(x, 'Bar')
+        y = ax.yaxis.get_label().get_text()
+        self.assertEqual(y, 'Thingness')
+
+    def test_yx_cube(self):
+        c = simple_2d()[:, 0]
+        c.transpose()
+        # Making the cube a vertical coordinate should change the default
+        # orientation of the plot.
+        c.coord('bar').attributes['positive'] = 'up'
+        qplt.plot(c)
+        ax = qplt.plt.gca()
+        x = ax.xaxis.get_label().get_text()
+        self.assertEqual(x, 'Thingness')
+        y = ax.yaxis.get_label().get_text()
+        self.assertEqual(y, 'Bar')
+
 if __name__ == "__main__":
     tests.main()