fix correlation function

Author: Eight1911

.travis.yml

@@ -8,6 +8,6 @@ notifications:
 sudo: false
 script:
   - if [[ -a .git/shallow ]]; then git fetch --unshallow; fi
-  - julia -e 'Pkg.clone(pwd()); Pkg.build("DecisionTree"); Pkg.test("DecisionTree"; coverage=true)'
+  - julia -e 'import Pkg; Pkg.clone(pwd()); Pkg.build("DecisionTree"); Pkg.test("DecisionTree"; coverage=true)'
 after_success:
-  - julia -e 'cd(Pkg.dir("DecisionTree")); Pkg.add("Coverage"); using Coverage; Coveralls.submit(Coveralls.process_folder())'
+  - julia -e 'import Pkg; cd(Pkg.dir("DecisionTree")); Pkg.add("Coverage"); using Coverage; Coveralls.submit(Coveralls.process_folder())'

src/measures.jl

@@ -160,10 +160,10 @@ function cor(x, y)
     x_centered = x .- x_mean
     y_centered = y .- y_mean
 
-    x_var = sum(x_centered .^ 2) / (n - 1)
-    y_var = sum(y_centered .^ 2) / (n - 1)
+    x_var = sum(x_centered .^ 2)
+    y_var = sum(y_centered .^ 2)
 
-    xy_cov = sum(x_centered .* y_centered) / n
+    xy_cov = sum(x_centered .* y_centered)
 
     return xy_cov / sqrt(x_var * y_var)