Extend plugins with imshow_collection

A first implementation is made for Matplotlib.

skimage/io/_plugins/matplotlib_plugin.ini

@@ -1,4 +1,3 @@
 [matplotlib]
 description = Display or save images using Matplotlib
-provides = imshow, imread, _app_show
-
+provides = imshow, imread, imshow_collection, _app_show

skimage/io/_plugins/matplotlib_plugin.py

@@ -147,6 +147,7 @@ def imshow(im, ax=None, show_cbar=None, **kwargs):
     if kwargs.get('cmap', None) == 'viridis':
         kwargs['cmap'] = viridis
     lo, hi, cmap = _get_display_range(im)
+
     kwargs.setdefault('interpolation', 'nearest')
     kwargs.setdefault('cmap', cmap)
     kwargs.setdefault('vmin', lo)
@@ -160,8 +161,20 @@ def imshow(im, ax=None, show_cbar=None, **kwargs):
         plt.colorbar(ax_im, cax=cax)
     ax.set_adjustable('box-forced')
     ax.get_figure().tight_layout()
+
     return ax_im
 
+
+def imshow_collection(ic, *args, **kwargs):
+    """Display all images in the collection.
+
+    """
+    fig, axes = plt.subplots(1, len(ic))
+    for n, image in enumerate(ic):
+        kwargs['axis'] = axes[n]
+        imshow(image, *args, **kwargs)
+
+
 imread = plt.imread
 show = plt.show
 

skimage/io/_plugins/test_plugin.ini

@@ -1,3 +1,3 @@
 [test]
 description = Test plugin
-provides = imsave, imshow, imread, imread_collection
+provides = imsave, imshow, imread, imread_collection, imshow_collection

skimage/io/_plugins/test_plugin.py

@@ -1,6 +1,8 @@
 # This mock-up is called by ../tests/test_plugin.py
 # to verify the behaviour of the plugin infrastructure
 
+from skimage.io import ImageCollection
+
 
 def imread(fname, dtype=None):
     assert fname == 'test.png'
@@ -20,3 +22,8 @@ def imshow(arr, plugin_arg=None):
 def imread_collection(x, conserve_memory=True):
     assert conserve_memory == False
     assert x == '*.png'
+    return ImageCollection([0, 1], load_func=lambda x: x)
+
+
+def imshow_collection(x):
+    assert len(x) == 2