My distance metric for vectors was stupid: let's try again

batterseapower · Sep 12, 2008 · 994b028 · 994b028
1 parent fdd4ac5
commit 994b028
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diff --git a/Algorithms/MachineLearning/Framework.hs b/Algorithms/MachineLearning/Framework.hs
@@ -2,6 +2,7 @@
 -- the machine learning algorithms.
 module Algorithms.MachineLearning.Framework where
 
+import Algorithms.MachineLearning.LinearAlgebra
 import Algorithms.MachineLearning.Utilities
 
 import Numeric.LinearAlgebra
@@ -126,7 +127,7 @@ instance MetricSpace Double where
     distance x y = abs (x - y)
 
 instance MetricSpace (Vector Double) where
-    distance = (<.>)
+    distance x y = vectorSumSquares (x - y)
 
 --
 -- Models

diff --git a/Algorithms/MachineLearning/LinearAlgebra.hs b/Algorithms/MachineLearning/LinearAlgebra.hs
@@ -56,6 +56,10 @@ applyVector fns inputs = fromList $ map ($ inputs) fns
 vectorSum :: Element a => Vector a -> a
 vectorSum v = constant 1 (dim v) <.> v
 
+-- | The sum of the squares of the elements of the vector
+vectorSumSquares :: Element a => Vector a -> a
+vectorSumSquares v = v <.> v
+
 -- | Mean of the elements in a vector.
 vectorMean :: Element a => Vector a -> a
 vectorMean v = (vectorSum v) / fromIntegral (dim v)