numpy中简单且实用的操作1

import random

import numpy as np
data = np.array([1,2,3])
print(data)
print(data.max())
print(np.ones(3))
print(np.zeros(3))
print(np.random.random(3))

data = np.array([1,2])
ones = np.ones(2)
print(data+ones)
print(data-ones)
print(data*data)
print(data/data)
print(data*1.6)

data = np.array([1,2,3])
print(data[0])
print(data[1])
print(data[0:2])
print(data[1:])
print(np.ones((3,2)))
print(np.zeros((3,2)))
np.random.random((3,2))
def ones_row(args):
    print(data + ones_row)
    pass

#numpy基本加减和取行操作
import numpy as np
from numpy import array

a = np.array([1,1,1,1])
b = np.array([[1],[1],[1],[1]])
a+b
print(a+b)
array([[2, 2, 2, 2],
[2, 2, 2, 2],
[2, 2, 2, 2],
[2, 2, 2, 2]]) # python的广播机制

c = np.array([[1,1,1,1]])
c+b
print(c+b)
array([[2, 2, 2, 2],
[2, 2, 2, 2],
[2, 2, 2, 2],
[2, 2, 2, 2]])
W = np.array([[1,1,1],[2,2,2]])
W[:,1]
array([1, 2])
print(W)
W[1]
array([2, 2, 2])
print(W)
W[:,1] = np.array([5,5])
W
array([[1, 5, 1],
[2, 5, 2]])
print(W)

#delet函数
import numpy as np
matrix = [
[1,2,3,4],
[5,6,7,8],
[9,10,11,12]
]
p1 = np.delete(matrix, 1, 0) # 第0维度(行)第1行被删除(初始行为0行)
print(">>>>p1>>>>\n",p1)
p2 = np.delete(matrix, 1, 1) # 第1维度(列)第1行被删除
print(">>>>p2>>>>\n",p2)
p3 = np.delete(matrix, 1) # 拉平后删除第1个元素(初始为第0个)
print(">>>>p3>>>>\n",p3)
p4 = np.delete(matrix, [0,1], 1) # 第1维度(列)第0、1行被删除
print(">>>>p4>>>>\n",p4)