add helper function for comparing plots

Author: nschloe

test/helpers.py

@@ -11,6 +11,7 @@
 
 import imagehash
 import matplotlib
+import matplotlib.image as mpimg
 import matplotlib.pyplot as plt
 from PIL import Image
 
@@ -151,6 +152,30 @@ def get_details(self):
         return
 
 
+def compare_with_latex(fig):
+
+    # Store original as PNG
+    _, prefix = tempfile.mkstemp()
+    filename = prefix + '.png'
+    plt.savefig(filename, bbox_inches='tight')
+
+    # Get PNG of LaTeX conversion
+    obj = Phash(fig)
+
+    # Display both
+    plt.figure()
+    plt.subplot(121)
+    img0 = mpimg.imread(filename)
+    plt.imshow(img0)
+    #
+    plt.subplot(122)
+    img1 = mpimg.imread(obj.png_file)
+    plt.imshow(img1)
+
+    plt.show()
+    return
+
+
 def print_tree(obj, indent=''):
     '''Recursively prints the tree structure of the matplotlib object.
     '''

test/test_basic_sin.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 #
-from helpers import Phash
+import helpers
 
 
 def plot():
@@ -24,5 +24,9 @@ def plot():
 
 
 def test():
-    phash = Phash(plot())
+    phash = helpers.Phash(plot())
     assert phash.phash == '1f36e5c621c1e7c1', phash.get_details()
+
+
+if __name__ == '__main__':
+    helpers.compare_with_latex(plot())

test/test_legends.py

@@ -33,3 +33,7 @@ def test():
     phash = helpers.Phash(plot())
     assert phash.phash == '7f7ca18386d10eaa', phash.get_details()
     return
+
+
+if __name__ == '__main__':
+    helpers.compare_with_latex(plot())