Avoid division by 0 in eval script

scripts/conll18_ud_eval.py

@@ -470,7 +470,9 @@ def evaluate(gold_ud, system_ud, extraColumns) :
         denom1 += (predictedValues[i]-predMean)**2
         denom2 += (goldValues[i]-goldMean)**2
         
-      pearson = numerator/((denom1**0.5)*(denom2**0.5))
+      pearson = 0.0
+      if denom1 > 0.0 and denom2 > 0.0 :
+        pearson = numerator/((denom1**0.5)*(denom2**0.5))
       R2 = pearson**2
     return [Score(gold, system, correct, aligned, isNumeric=isNumericOnly, R2=R2), errors]