diff --git a/doc/source/example/comparing/ridf.py b/doc/source/example/comparing/ridf.py
new file mode 100644
index 0000000000000000000000000000000000000000..a52ffb0c3464584ca3068b646062944a49deceb5
--- /dev/null
+++ b/doc/source/example/comparing/ridf.py
@@ -0,0 +1,33 @@
+import numpy as np
+import matplotlib.pyplot as plt
+from navipy.database import DataBaseLoad
+from navipy.comparing import rot_imagediff
+import pkg_resources
+
+
+# 1) Connect to the database
+mydb_filename = pkg_resources.resource_filename(
+    'navipy', 'resources/database.db')
+mydb = DataBaseLoad(mydb_filename)
+# 2) Define the position-orinetation at which
+# we want the image and get the scene
+rowid = 12
+my_scene_memory = mydb.scene(rowid=rowid)
+rowid = 1
+my_scene_current = mydb.scene(rowid=rowid)
+
+# Calculate image rot diff
+rotdf = rot_imagediff(my_scene_current, my_scene_memory)
+rotdf = np.roll(rotdf, 180, axis=0)
+f, axarr = plt.subplots(1, 2, figsize=(15, 4))
+for chan_i, chan_n in enumerate(mydb.channels):
+    if chan_n == 'D':
+        color = 'k'
+        ax = axarr[1]
+    else:
+        color = chan_n
+        ax = axarr[0]
+    ax.plot(rotdf[:, chan_i], color=color)
+
+    
+f.show()
diff --git a/navipy/comparing/__init__.py b/navipy/comparing/__init__.py
index a871b809565e865f0d88376fd0a84906cb90d40d..e33ae9059e0c986705006cc285315ebfd125c282 100644
--- a/navipy/comparing/__init__.py
+++ b/navipy/comparing/__init__.py
@@ -48,9 +48,6 @@ the current and memorised place code
     :returns: the image difference
     :rtype: float #array(1,4) for ibpc and float for obpc
 
-    ..ref: Zeil, J., 2012. Visual homing: an insect perspective.
-           Current opinion in neurobiology
-
     """
     simple_diff = simple_imagediff(current, memory)
     diff = np.power(simple_diff, 2)
@@ -76,6 +73,10 @@ the current and memorised place code.
     ..note: assume that the image is periodic along the x axis
            (the left-right axis)
 
+    .. literalinclude:: example/comparing/ridf.py
+       :lines: 4,20
+
+    .. plot:: example/comparing/ridf.py
     """
     if not is_ibpc(current):  # and not is_obpc(current):
         raise TypeError('The current and memory place code\
diff --git a/todo b/todo
index e54bfd07a7f7d3a9a780c43bf633619a486fd2a3..c072d18683019c20eb97c925d53b2bde322c3c9a 100644
--- a/todo
+++ b/todo
@@ -32,40 +32,4 @@
    3. Ring-attractor (Goldschmidt 2017)
    4. Ring-attractor (Stone 2017)
 
-
-------------------------------------------------------
-Are those below still to do ?
-------------------------------------------------------
-0003: Improve database
-In the init database I would like to use class properties instead of get/read
-line: 263,273,and 394
-    def create(self)
-should be replaced by:
-    @property
-    def create(self)
-
-It implies that at every point that self.create() is called should be changed to self.create [Note the absence of parenthesis]
-
-line: 298
-    def get_posorients(self) 
-should be replaced by
-    @property
-    def posorients(self)
-
-Need to propagate the changes through all the code (see rendering / processing / moving )
-
-Should be done, but maybe I missed something?
-
-------------------------------------------------------
-0005: Write test function for raise Error
-- for every raise error create a test function, checking that the error is correctly thrown (see moving/test_agent for inspiration)
-
-also should be done. But I did not add any more checks to the moving part, shall I check for additional possible checks?
-
-
---------------------------------------------------------------------
-0009: can the last dimension (4) of the place-code be greater 1? (should be 1)
-    Yes it can, see apcv a [1x1x1x3] array 
-0010: what is the image in the database? must it be transformed to a a scene?
-    The image is an image, and distance the distance. I added scene as a join image+distance array
-    now we do not have a  read_image function in database anymore, is it supposed to be like this?
+0005: Change output of comparing to be consistent with place code
\ No newline at end of file