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Something wrong about the calculation of precision and recall #113

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WinChua opened this issue Dec 6, 2017 · 0 comments

WinChua commented Dec 6, 2017

crab/scikits/crab/metrics/metrics.py

Lines 319 to 323 in beb3555

    
           precision[i] = (intersection_size / float(len(y_real[i]))) \ 
        
                                   if len(y_real[i])  else 0.0 
        
           recall[i] = (intersection_size / float(len(y_items_pred))) \ 
        
                                   if len(y_items_pred) else 0.0

I doubt that the calculation of precision and recall is wrong.

The definition of precision is the proportion of the recommendation list (the y_pred) which is contained in the true list(the y_real).

So, I think the calculation of precision should be
precision[i] = (intersection_size / float(len(y_items_pred)))
if len(y_items_pred) else 0.0

and similarly, the calculation of recall should be
recall[i] = (intersection_size / float(len(y_real[i])))
if len(y_real[i]) else 0.0

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