implement mean absolute error

src/GEval/Core.hs

@@ -5,6 +5,7 @@
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 
+
 module GEval.Core
     ( geval,
       gevalCore,
@@ -88,7 +89,7 @@ defaultLogLossHashedSize = 10
 -- | evaluation metric
 data Metric = RMSE | MSE | BLEU | Accuracy | ClippEU | FMeasure Double | NMI
               | LogLossHashed Word32 | CharMatch | MAP | LogLoss | Likelihood
-              | BIOF1 | BIOF1Labels | LikelihoodHashed Word32
+              | BIOF1 | BIOF1Labels | LikelihoodHashed Word32 | MAE
               deriving (Eq)
 
 instance Show Metric where
@@ -117,6 +118,9 @@ instance Show Metric where
   show Likelihood = "Likelihood"
   show BIOF1 = "BIO-F1"
   show BIOF1Labels = "BIO-F1-Labels"
+  show MAE = "MAE"
+
+
 
 instance Read Metric where
   readsPrec _ ('R':'M':'S':'E':theRest) = [(RMSE, theRest)]
@@ -140,6 +144,7 @@ instance Read Metric where
   readsPrec _ ('M':'A':'P':theRest) = [(MAP, theRest)]
   readsPrec _ ('B':'I':'O':'-':'F':'1':'-':'L':'a':'b':'e':'l':'s':theRest) = [(BIOF1Labels, theRest)]
   readsPrec _ ('B':'I':'O':'-':'F':'1':theRest) = [(BIOF1, theRest)]
+  readsPrec _ ('M':'A':'E':theRest) = [(MAE, theRest)]
 
 data MetricOrdering = TheLowerTheBetter | TheHigherTheBetter
 
@@ -160,6 +165,7 @@ getMetricOrdering LogLoss = TheLowerTheBetter
 getMetricOrdering Likelihood = TheHigherTheBetter
 getMetricOrdering BIOF1 = TheHigherTheBetter
 getMetricOrdering BIOF1Labels = TheHigherTheBetter
+getMetricOrdering MAE = TheLowerTheBetter
 
 isInputNeeded :: Metric -> Bool
 isInputNeeded CharMatch = True
@@ -403,9 +409,13 @@ gevalCore' :: (MonadIO m, MonadThrow m, MonadUnliftIO m) =>
            -> LineSource (ResourceT m)  -- ^ source to read the expected output
            -> LineSource (ResourceT m)  -- ^ source to read the output
            -> m (MetricValue)           -- ^ metric values for the output against the expected output
-gevalCore' MSE _ = gevalCoreWithoutInput outParser outParser itemError averageC id
+gevalCore' MSE _ = gevalCoreWithoutInput outParser outParser itemSquaredError averageC id
   where outParser = getValue . TR.double
 
+gevalCore' MAE _ = gevalCoreWithoutInput outParser outParser itemAbsoluteError averageC id
+  where outParser = getValue . TR.double
+
+
 gevalCore' LogLoss _ = gevalCoreWithoutInput outParser outParser itemLogLossError averageC id
   where outParser = getValue . TR.double
 
@@ -660,8 +670,12 @@ items (LineSource lineSource _ _) parser =
   where toItem (Right x) = Got x
         toItem (Left m) = Wrong m
 
-itemError :: (Double, Double) -> Double
-itemError (exp, out) = (exp-out)**2
+itemAbsoluteError :: (Double, Double) -> Double
+itemAbsoluteError (exp, out) = abs (exp-out)
+
+itemSquaredError :: (Double, Double) -> Double
+itemSquaredError (exp, out) = (exp-out)**2
+
 
 itemLogLossError :: (Double, Double) -> Double
 itemLogLossError (exp, out)

test/Spec.hs

@@ -51,6 +51,9 @@ main = hspec $ do
   describe "mean square error" $ do
     it "simple test with arguments" $
       runGEvalTest "mse-simple" `shouldReturnAlmost` 0.4166666666666667
+  describe "mean absolute error" $ do
+    it "simple test with arguments" $
+      runGEvalTest "mae-simple" `shouldReturnAlmost` 1.5
   describe "BLEU" $ do
     it "trivial example from Wikipedia" $
       runGEvalTest "bleu-trivial" `shouldReturnAlmost` 0.0

test/mae-simple/mae-simple-solution/test-A/out.tsv

@@ -0,0 +1,3 @@
+34.0
+26.0
+18.5

test/mae-simple/mae-simple/config.txt

@@ -0,0 +1 @@
+--metric MAE

test/mae-simple/mae-simple/test-A/expected.tsv

@@ -0,0 +1,3 @@
+30.0
+26.5
+18.5