Python numpy中切片 [:, : -1] [:, [-1] ] 分别表示什么

文章目录

• 前言
• 一、[ : , : -1]表示如图所示
• 二、[ : , [-1]]表示如图所示
• 三、[ : , -1]表示如图所示
• 总结

---

前言

---

一、[ : , : -1]表示如图所示

import numpy as np
xy = [
    [1, 2, 3, 4, 5],
    [6, 7, 8, 9, 10],
    [11, 12, 13, 14, 15],
    [16, 17, 18, 19, 20],
    [21, 22, 23, 24, 25],
]
xy = np.array(xy)
x_data = xy[:,:-1]
print(x_data)

[[ 1  2  3  4]
 [ 6  7  8  9]
 [11 12 13 14]
 [16 17 18 19]
 [21 22 23 24]]

二、[ : , [-1]]表示如图所示

import numpy as np
xy = [
    [1, 2, 3, 4, 5],
    [6, 7, 8, 9, 10],
    [11, 12, 13, 14, 15],
    [16, 17, 18, 19, 20],
    [21, 22, 23, 24, 25],
]
xy = np.array(xy)
x_data = xy[:,[-1]]
print(x_data)

[[ 5]
 [10]
 [15]
 [20]
 [25]]

三、[ : , -1]表示如图所示

import numpy as np
xy = [
    [1, 2, 3, 4, 5],
    [6, 7, 8, 9, 10],
    [11, 12, 13, 14, 15],
    [16, 17, 18, 19, 20],
    [21, 22, 23, 24, 25],
]
xy = np.array(xy)
x_data = xy[:,-1]
print(x_data)

---

[ 5 10 15 20 25]

总结

讲不清楚，直接举例说明。

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