scikit-learn Cookbook - Second Edition

NumPy broadcasting

8. Add 1 to every element of the array by broadcasting. Note that changes to the array are not saved:

array_1 + 1array([[ 1,  2],       [ 3,  4],       [ 5,  6],       [ 7,  8],       [ 9, 10]])

The term broadcasting refers to the smaller array being stretched or broadcast across the larger array. In the first example, the scalar 1 was stretched to a 5 x 2 shape and then added to array_1.

9. Create a new array_2 array. Observe what occurs when you multiply the array by itself (this is not matrix multiplication; it is element-wise multiplication of arrays):

array_2 = np.arange(10)array_2 * array_2array([ 0,  1,  4,  9, 16, 25, 36, 49, 64, 81])

10. Every element has been squared. Here, element-wise multiplication has occurred. Here is a more complicated example: ...