数组运算
不需要循环即可对数据进行批量运算,叫做矢量化运算. 不同形状的数组之间的算数运算,叫做广播.
import numpy as np
ndarray1 = np.array([1, 2, 3, 4, 5])
ndarray2 = np.array([3, 4, 5, 6, 7])
# 数组和数组之间的运算
ndarray3 = ndarray1 * ndarray2
ndarray4 = ndarray1 + ndarray2
# 数组和数字值之间的运算
ndarray5 = ndarray1 + 100
ndarray6 = 5 / ndarray1
# 多维数组和多维数组之间的运算
ndarray7 = np.arange(9).reshape((3, 3))
ndarray8 = np.arange(9).reshape((3, 3))
ndarray9 = ndarray7 + ndarray8
# 一维数组和多维数组之间运算
ndarray10 = np.arange(3)
ndarray11 = np.arange(6).reshape((2, 3))
ndarray12 = ndarray10 + ndarray11
输出结果:
ndarray3: [ 3 8 15 24 35]
ndarray4: [ 4 6 8 10 12]
ndarray5: [101 102 103 104 105]
ndarray6: [ 5. 2.5 1.66666667 1.25 1. ]
ndarray9: [[ 0 2 4]
[ 6 8 10]
[12 14 16]]
ndarray10: [0 1 2]
ndarray11: [[0 1 2]
[3 4 5]]
ndarray12: [[0 2 4]
[3 5 7]]