# -*- encoding:utf-8 -*-

# Copyright (c) 2015 Shiye Inc.

# All rights reserved.

#

# Author: ldq <liangduanqi@shiyejinrong.com>

# Date: 2019/2/11 14:57

import numpy as np

a = np.arange(2, 14).reshape(3, 4)

'''

reshape矩阵变维

[[ 2  3  4  5]

 [ 6  7  8  9]

 [10 11 12 13]]

'''

a_arg_max = np.argmax(a)

'''

返回最大索引

11

'''

mean_a = np.mean(a)

'''

mean平均值

7.5

'''

avg_a = np.average(a)

'''

average加权平均值

7.5

'''

mean_x = np.mean(np.array([1,2,3,4,5]))

average_x = np.average(np.array([1,2,3,4,5]), weights=np.array([1,1,1,1,1]))

median_a = np.median(a)

'''

median中位数

7.5

'''

cumsum_a = np.cumsum(a)

'''

cumsum元素累加

[ 2  5  9 14 20 27 35 44 54 65 77 90]

'''

diff_a = np.diff(a, axis=0)

'''

数值差分

[[4 4 4 4]

 [4 4 4 4]]

'''

nonzero_a = np.nonzero(a)

'''

nonzero这个函数将所有非零元素的行与列坐标分割开，重构成两个分别关于行和列的矩阵

(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))

'''

sort_a = np.sort(a,axis=-1,kind='mergesort')

transpose_a = np.transpose(a)

transpose_a_2 = a.T

'''

矩阵的转置

transpose

'''

clip_a = np.clip(a,5,9)

'''

clip指定的元素转换为最小值或者最大值

[[5 5 5 5]

 [6 7 8 9]

 [9 9 9 9]]

'''