Python NumPy - Numerical Operations on Arrays

Arrays have a unique advantage over Python lists in that they allow you to perform element-wise operations without the need for a for loop. This makes computations very efficient specially while dealing with large data sets.

Suppose we have a list and we want to multiply all its elements by 3 (scalar). If we try to directly multiply it by three, it will just add the list elements three times, which is not what we wanted.

1>>> a = [1,3,5]
2>>> a*3
3[1, 3, 5, 1, 3, 5, 1, 3, 5]
4>>>
5

To get the right results, you will use the for-loop approach which would look as follows:

1>>> a = [1,3,5]
2>>> b = [3*x for x in a]
3