Compute co-occurrence matrix by counting values in cells

Question

I have a dataframe like this

df = pd.DataFrame({\'a\' : [1,1,0,0], \'b\': [0,1,1,0], \'c\': [0,0,1,1]})

I want to get

  a         


        

Answer 1

Numpy matmul

np.matmul(df.values.T,df.values)
Out[87]: 
array([[2, 1, 0],
       [1, 2, 1],
       [0, 1, 2]], dtype=int64)

#pd.DataFrame(np.matmul(df.values.T,df.values), df.columns, df.columns)