《NumPy Beginner's Guide》笔记Chapter1

# -*- coding: utf-8 -*-
#日期 = 23:33


""" 1. Imagine that we want to add two vectors called a and b The vector a holds the squares of integers 0 to n, for instance, if n is equal to 3, then a is equalto 0, 1, or 4. The vector b holds the cubes of integers 0 to n, so if n is equal to 3, then the vector b is equal to 0, 1, or 8. """

#plain Python 实现
def pythonsum(n):
    a = range(n)
    b = range(n)
    c = []

    for i in range(len(a)):
        a[i] = i ** 2
        b[i] = i ** 3
        c.append(a[i] + b[i])
    return  c

#numpy 实现
import numpy as np

def numpysum(n):
    a = np.arange(n) ** 2
    b = np.arange(n) ** 3
    c = a + b
    return c

import time
tic = time.time()
for i in range(10000):   #循环10000次
    c = pythonsum(1000)
toc = time.time()
print("The execute time of python is %f s" % (toc - tic))


tic = time.time()
for i in range(10000):   #循环10000次
    c = numpysum(1000)
toc = time.time()
print("The execute time of numpy is %f s" % (toc - tic))


""" 输出： The execute time of python is 3.842000 s The execute time of numpy is 0.916000 s """