Minor cleanups

* PEP8 clean ups (space after commas, docstring spacing, prefer parentheses over line continuation)
* Simplify creation of test images.
* Use `plt.subplots` instead of state machine
* Minor wording modifications

doc/examples/plot_edge_filter.py

@@ -1,23 +1,20 @@
-import matplotlib
 import matplotlib.pyplot as plt
 
 from skimage.data import camera
-from skimage.filter import roberts,sobel
+from skimage.filter import roberts, sobel
 
 image = camera()
 edge_roberts = roberts(image)
 edge_sobel = sobel(image)
 
-plt.figure(figsize=(8, 2.5))
-plt.subplot(1, 2, 1)
-plt.imshow(edge_roberts, cmap=plt.cm.gray)
-plt.title('Roberts Edge Detection')
-plt.axis('off')
+fig, (ax0, ax1) = plt.subplots(ncols=2)
 
-plt.subplot(1, 2, 2)
-plt.imshow(edge_sobel, cmap=plt.cm.gray)
-plt.title('Sobel Edge Detection')
-plt.axis('off')
+ax0.imshow(edge_roberts, cmap=plt.cm.gray)
+ax0.set_title('Roberts Edge Detection')
+ax0.axis('off')
 
+ax1.imshow(edge_sobel, cmap=plt.cm.gray)
+ax1.set_title('Sobel Edge Detection')
+ax1.axis('off')
 
 plt.show()