对数组做基本的算术运算,将会对整个数组的所有元组进行逐一运算,并将运算结果保存在一个新的数组内,而不会破坏原始的数组
数组和向量之间的运算
数组和数组之间的运算
通用函数的使用
数组和向量之间的运算
1 2 3 4 5 6
import numpy as npa = np.array([20 ,40 ,50 ,80 ]) b = np.arange(4 ) print(a) print(b)
[20 40 50 80]
[0 1 2 3]
array([20, 39, 48, 77])
array([0, 1, 4, 9], dtype=int32)
array([ 9.12945251, 7.4511316 , -2.62374854, -9.93888654])
array([ True, False, False, False])
array([50, 80])
数组和数组之间的运算
1 2 3 4 5 6 7
A = np.array( [[1 ,1 ], [0 ,1 ]]) B = np.array( [[2 ,0 ], [3 ,4 ]]) print(A) B
[[1 1]
[0 1]]
array([[2, 0],
[3, 4]])
四则运算
[[-1 1]
[-3 -3]]
array([[2, 0],
[0, 4]])
向量点乘的实现
array([[5, 4],
[3, 4]])
array([[5, 4],
[3, 4]])
array([[5, 4],
[3, 4]])
自加和自乘
array([[3, 1],
[3, 5]])
array([[ 6, 0],
[ 9, 20]])
聚合函数
8.75
20
0
指定行列的聚合
1 2
c = np.array(np.arange(12 ).reshape(3 ,4 )) c
array([[ 0, 1, 2, 3],
[ 4, 5, 6, 7],
[ 8, 9, 10, 11]])
array([ 6, 22, 38])
array([4., 5., 6., 7.])
array([[ 0, 1, 3, 6],
[ 4, 9, 15, 22],
[ 8, 17, 27, 38]], dtype=int32)
sort函数
Signature: np.sort(a, axis=-1, kind=‘quicksort’, order=None)
axis : int or None, optional
Axis along which to sort. If None, the array is flattened before
sorting. The default is -1, which sorts along the last axis.
kind : {‘quicksort’, ‘mergesort’, ‘heapsort’, ‘stable’}, optional
Sorting algorithm. Default is ‘quicksort’.
array([[ 0, 1, 2, 3],
[ 4, 5, 6, 7],
[ 8, 9, 10, 11]])
1 2
d = np.array([[1 ,6 ,2 ],[6 ,1 ,3 ],[1 ,5 ,2 ]]) d
array([[1, 6, 2],
[6, 1, 3],
[1, 5, 2]])
array([[1, 1, 2],
[1, 5, 2],
[6, 6, 3]])
通用函数
all
any
argmax
argmin
argsort
average
diff
array([[ 0, 1, 2, 3],
[ 4, 5, 6, 7],
[ 8, 9, 10, 11]])
array([[1.00000000e+00, 2.71828183e+00, 7.38905610e+00, 2.00855369e+01],
[5.45981500e+01, 1.48413159e+02, 4.03428793e+02, 1.09663316e+03],
[2.98095799e+03, 8.10308393e+03, 2.20264658e+04, 5.98741417e+04]])
array([[0. , 1. , 1.41421356, 1.73205081],
[2. , 2.23606798, 2.44948974, 2.64575131],
[2.82842712, 3. , 3.16227766, 3.31662479]])
array([[ 0, 2, 4, 6],
[ 8, 10, 12, 14],
[16, 18, 20, 22]])
array([[ 0, 2, 4, 6],
[ 8, 10, 12, 14],
[16, 18, 20, 22]])
array([[0, 0, 0, 0],
[1, 1, 1, 1],
[2, 2, 2, 2]], dtype=int64)
array([[0, 1, 2, 3],
[0, 1, 2, 3],
[0, 1, 2, 3]], dtype=int64)
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