scikit-learn Cookbook - Second Edition

Arithmetic operations

25. Add all the elements of the array with the sum method. Go back to array_1:

array_1array([[ 1,  2],       [ 3,  4],       [ 5,  6],       [ 7,  8],       [ 9, 10]])array_1.sum()55

26. Find all the sums by row:

array_1.sum(axis = 1)array([ 3,  7, 11, 15, 19])

27. Find all the sums by column:

array_1.sum(axis = 0)array([25, 30])

28. Find the mean of each column in a similar way. Note that the dtype of the array of averages is np.float:

array_1.mean(axis = 0)array([ 5.,  6.])