python学习

Posted 2021-01-13 G.Z.Bing

numpy.array[  ]

#!/usr/bin/python3
# -*- coding: utf-8 -*-
# @Time    : 18-10-17 上午10:51
# @Author  : Guo Zhengbing
# @Email   : [email protected]

import numpy

# print(help(numpy.genfromtxt))
a = numpy.array([5, 10, 25, 30])
b = numpy.array([[5, 1, 2], [23, 4, 9]])
# print(a)
# print(b) # 输出矩阵

# print(a.shape) # 输出这个矩阵的类型 N行M列
# print(b.shape)

# numbers = numpy.array([1, 2, 3, 4, ‘5‘])
# print(numbers)
# print(numbers.dtype) # 输出类型
# 保证同一类型

# print(a[0:3]) # 矩阵切片

# print(b[:, 0]) # 取一个矩阵第1列
# print(b[:, 0: 2]) # 取一个矩阵前两列

matrix = numpy.array([
               [5, 10, 15],
               [3, 6, 9],
               [8, 7, 13]
            ])
# print(matrix[1:3, 0:2]) # 取几行几列

a = numpy.array([5, 10, 25, 30])
# a == 10
# print(a == 10) # 判断数组中各个元素是否是10
# print(matrix == 10) # 判断数组中各个元素是否是10

# equal = (a == 10)
# print(equal)
# print(a[equal]) #返回真实值