Made a change to mean calculation

Y[1,R[1,:]] was indexing over the columns given by R[1,:] which returns binary values and thereby iterating over indexes 0 and 1 of Y[1].

Author: Vignesh Kumar

notebooks/ml/ML-Exercise8.ipynb

@@ -1045,7 +1045,7 @@
     }
    ],
    "source": [
-    "Y[1,R[1,:]].mean()"
+    "Y[1,np.where(R[1,:]==1)[0]].mean()"
    ]
   },
   {