Time for action – reading and writing files

As an example of file I/O, we will create an identity matrix and store its contents in a file.

Note

In this and other chapters, we will use the following line by convention to import NumPy:

import numpy as np

Perform the following steps to do so:

1. The identity matrix is a square matrix with ones on the main diagonal and zeros for the rest (see https://www.khanacademy.org/math/precalculus/precalc-matrices/zero-identity-matrix-tutorial/v/identity-matrix).

   The identity matrix can be created with the eye() function. The only argument that we need to give the eye() function is the number of ones. So, for instance, for a two-by-two matrix, write the following code:

   i2 = np.eye(2)
   print(i2)

   The output is:

   [[ 1.  0.]
   [ 0.  1.]]

2. Save the data in a plain text file with the savetxt() function. Specify the name of the file that we want to save the data in and the array containing the data itself:

   np.savetxt("eye.txt", i2)

A file called eye.txt should...