Gallery: show colour bar stealing space from multiple axes

.github/workflows/benchmarks_run.yml

@@ -29,7 +29,7 @@ jobs:
     env:
       IRIS_TEST_DATA_LOC_PATH: benchmarks
       IRIS_TEST_DATA_PATH: benchmarks/iris-test-data
-      IRIS_TEST_DATA_VERSION: "2.19"
+      IRIS_TEST_DATA_VERSION: "2.21"
       # Lets us manually bump the cache to rebuild
       ENV_CACHE_BUILD: "0"
       TEST_DATA_CACHE_BUILD: "2"

.github/workflows/ci-tests.yml

@@ -50,7 +50,7 @@ jobs:
             session: "tests"
 
     env:
-      IRIS_TEST_DATA_VERSION: "2.19"
+      IRIS_TEST_DATA_VERSION: "2.21"
       ENV_NAME: "ci-tests"
 
     steps:

docs/gallery_code/meteorology/plot_COP_maps.py

@@ -171,23 +171,13 @@ def main():
         )
         plt.gca().coastlines()
 
-    # Now add a colourbar who's leftmost point is the same as the leftmost
-    # point of the left hand plot and rightmost point is the rightmost
-    # point of the right hand plot.
-
-    # Get the positions of the 2nd plot and the left position of the 1st plot.
-    left, bottom, width, height = ax_array[1].get_position().bounds
-    first_plot_left = ax_array[0].get_position().bounds[0]
-
-    # The width of the colorbar should now be simple.
-    width = left - first_plot_left + width
-
-    # Add axes to the figure, to place the colour bar.
-    colorbar_axes = fig.add_axes([first_plot_left, 0.18, width, 0.03])
-
-    # Add the colour bar.
+    # Now add a colour bar which spans the two plots.  Here we pass Figure.axes
+    # which is a list of all (two) axes currently on the figure.  Note that
+    # these are different to the contents of ax_array, because those were
+    # standard Matplotlib Axes that Iris automatically replaced with Cartopy
+    # GeoAxes.
     cbar = plt.colorbar(
-        contour_result, colorbar_axes, orientation="horizontal"
+        contour_result, ax=fig.axes, aspect=60, orientation="horizontal"
     )
 
     # Label the colour bar and add ticks.

docs/src/whatsnew/latest.rst

@@ -75,6 +75,10 @@ This document explains the changes made to Iris for this release
 #. `@trexfeathers`_ documented the intended use of warnings filtering with
    Iris. See :ref:`filtering-warnings`. (:pull:`5509`)
 
+#. `@rcomer`_ updated the
+   :ref:`sphx_glr_generated_gallery_meteorology_plot_COP_maps.py` to show how
+   a colourbar may steal space from multiple axes. (:pull:`5537`)
+
 
 💼 Internal
 ===========

lib/iris/tests/results/imagerepo.json

@@ -1,6 +1,6 @@
 {
     "gallery_tests.test_plot_COP_1d.0": "aefec91c3601249cc9b3336dc4c8cdb31a64c6d997b3c0eccb5932d285e42f33",
-    "gallery_tests.test_plot_COP_maps.0": "ea9130db95668524913e6ac168991f0d956e917ec76396b96a853dcf94696935",
+    "gallery_tests.test_plot_COP_maps.0": "ea91789995668566913e43474adb6a917e8d947c4b46957ec6716a91958e6f81",
     "gallery_tests.test_plot_SOI_filtering.0": "fa56f295c5e0694a3c17a58d95e8da536233da99984c5af4c6739b4a9a444eb4",
     "gallery_tests.test_plot_TEC.0": "e5a761b69a589a4bc46f9e48c65c6631ce61d1ce3982c13739b33193c0ee3f8c",
     "gallery_tests.test_plot_anomaly_log_colouring.0": "ec4464e384a39b13931a9b1c85696da968d5e6e63e26847bdbd399938d3c5a4c",