15.3.2 Timing with the Python module timeit

Python provides the module timeit, which can be used to measure execution time. It requires that, first, a time object is constructed. It is constructed from two strings: a string with setup commands and a string with the commands to be executed.

We take the same four alternatives as in the preceding example. The array and function definitions are written now in a string called setup_statements and four timing objects are constructed as follows:

import timeit
setup_statements="""
from scipy import zeros
from numpy import where
A=zeros((1000,1000))
A[57,63]=10.

def find_elements_1(A):
    b = []
    n, m = A.shape
    for i in range(n):
        for j in range(m):
            if abs(A[i, j]) > 1.e-10:
               b.append(A[i, j])
    return b

def find_elements_2(A):
    return [a for a in A.reshape((-1,)) if abs(a) > 1.e-10]

def find_elements_3(A):
    return [a for a in A.flatten() if...