From bf2a5a429b5853a08ab3a18b261c0deb848e59f6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johannes=20Sch=C3=B6nberger?= <jschoenberger@demuc.de>
Date: Wed, 1 May 2013 12:57:30 +0200
Subject: [PATCH] Add residuals method to geometric transforms

---
 skimage/transform/_geometric.py | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/skimage/transform/_geometric.py b/skimage/transform/_geometric.py
index 4b2a38d5..1fcb55bb 100644
--- a/skimage/transform/_geometric.py
+++ b/skimage/transform/_geometric.py
@@ -61,6 +61,28 @@ class GeometricTransform(object):
         # well- and over-determined.
         return False
 
+    def residuals(self, src, dst):
+        """Determine residuals of transformed destination coordinates.
+
+        For each transformed source coordinate the euclidean distance to the
+        respective destination coordinate is determined.
+
+        Parameters
+        ----------
+        src : (N, 2) array
+            Source coordinates.
+        dst : (N, 2) array
+            Destination coordinates.
+
+        Returns
+        -------
+        residuals : (N, ) array
+            Residual for coordinate.
+
+        """
+
+        return np.sqrt(np.sum((self(src) - dst) ** 2, axis=1))
+
     def __add__(self, other):
         """Combine this transformation with another.