Show add comparison to python example

docs/docs/api_docs/python_api.md

@@ -1,26 +1,49 @@
 # Python API
 
-The Python API is a light wrapper of the C API. It creates an object that has [all the C functions](c_api/functions.md):
+The Python API is a light wrapper of the C API. It creates an object that has [all the C functions](c_api/functions.md). Here is a fictional example that, given a `MagicalImageURLGenerator` and a `CatFaceRecognitionModel`, will find cat faces most similar to the cats in a query image.
 
     from brpy import init_brpy
+    import requests # or whatever http request lib you prefer
+    import MagicalImageURLGenerator # made up
 
     # br_loc is /usr/local/lib by default,
     # you may change this by passing a different path to the shared objects
     br = init_brpy(br_loc='/path/to/libopenbr')
     br.br_initialize_default()
-
-    img = open('catpic.jpg','rb').read()
-
-    br.br_set_property('algorithm','MyCatFaceDetectionModel')
+    br.br_set_property('algorithm','CatFaceRecognitionModel') # also made up
     br.br_set_property('enrollAll','true')
 
-    tmpl = br.br_load_img(img, len(img))
-    catfaces = br.br_enroll_template(tmpl)
-
-    print('This pic has %i cats in it!' % br.br_num_templates(catfaces))
-
-    br.br_free_template(tmpl)
-    br.br_free_template_list(catfaces)
+    mycatsimg = open('mycats.jpg', 'rb').read() # cat picture not provided =^..^=
+    mycatstmpl = br.br_load_img(mycatsimg, len(mycatsimg))
+    query = br.br_enroll_template(mycatstmpl)
+    nqueries = br.br_num_templates(query)
+
+    scores = []
+    for imurl in MagicalImageURLGenerator():
+        # load and enroll image from URL
+        img = requests.get(imurl).content
+        tmpl = br.br_load_img(img, len(img))
+        targets = br.br_enroll_template(tmpl)
+        ntargets = br.br_num_templates(targets)
+
+        # compare and collect scores
+        scoresmat = br.br_compare_template_lists(targets, query)
+        for r in range(ntargets):
+            for c in range(nqueries):
+                scores.append((imurl, br.br_get_matrix_output_at(scoresmat, r, c)))
+
+        # clean up - no memory leaks
+        br.br_free_template(tmpl)
+        br.br_free_template_list(targets)
+
+    # print top 10 match URLs
+    scores.sort(key=lambda s: s[1])
+    for s in scores[:10]:
+        print(s[0])
+
+    # clean up - no memory leaks
+    br.br_free_template(mycatstmpl)
+    br.br_free_template_list(query)
     br.br_finalize()
 
 To enable the module, add `-DBR_INSTALL_BRPY=ON` to your cmake command (or use the ccmake GUI - highly recommended).