Learning NumPy Array

Selecting array elements

From time to time, we will want to select a particular element of an array. We will take a look at how to do this, but first, let's create a 2 x 2 matrix again (see the elementselection.py file in the Chapter02 folder of this book's code bundle):

In: a = array([[1,2],[3,4]])
In: a
Out:
array([[1, 2],       [3, 4]])

The matrix was created this time by passing a list of lists to the array() function. We will now select each item of the matrix one at a time, as shown in the following code snippet. Remember, the indices are numbered starting from 0.

In: a[0,0]
Out: 1
In: a[0,1]
Out: 2
In: a[1,0]
Out: 3
In: a[1,1]
Out: 4

As you can see, selecting elements of the array is pretty simple. For the array a, we just use the notation a[m,n] ...