如何向numpy数组添加常量,但在Python中跳过第一行

要做到这一点,首先,您需要了解numpy的基本操作。

arr 看起来像下面这样。

arr = np.array([[ 0.08778,  0.99666,  0.30648],
   [ 0.41688,  2.70076,  1.10135],
   [ 1.90494,  0.91685, -0.26984],
   [-0.44512,  1.73972, -1.24406],
   [-1.68572,  1.01617,  1.01221],
   [-0.1977 , -0.77177, -0.35553],
   [ 0.61588,  3.6995 ,  1.59813],
   [ 2.98863,  0.86173, -0.59616],
   [-0.78312,  2.20935, -2.22362],
   [-2.73208,  1.02071,  1.44702],
   [-0.36006, -1.82939, -0.72827]])

这是一个二维numpy数组。所以您可以访问任何行和列,甚至是特定位置的特定值。要遍历数组,可以使用 arr[starting row: ending row, starting column: ending column] . 例如,您希望通过 arr[1:,:] .

arr[1:,:] = arr[1:,:]+0.1 or arr[1:,:]+=0.1 or arr[1:]+=0.1

array([[ 0.08778,  0.99666,  0.30648],
   [ 0.51688,  2.80076,  1.20135],
   [ 2.00494,  1.01685, -0.16984],
   [-0.34512,  1.83972, -1.14406],
   [-1.58572,  1.11617,  1.11221],
   [-0.0977 , -0.67177, -0.25553],
   [ 0.71588,  3.7995 ,  1.69813],
   [ 3.08863,  0.96173, -0.49616],
   [-0.68312,  2.30935, -2.12362],
   [-2.63208,  1.12071,  1.54702],
   [-0.26006, -1.72939, -0.62827]])

因为您不想操作列,所以您可以编写代码而不必提及列。

你可以这样做:

import numpy as np

a = np.array([[ 0.08778,  0.99666,  0.30648],
       [ 0.41688,  2.70076,  1.10135],
       [ 1.90494,  0.91685, -0.26984],
       [-0.44512,  1.73972, -1.24406],
       [-1.68572,  1.01617,  1.01221],
       [-0.1977 , -0.77177, -0.35553],
       [ 0.61588,  3.6995 ,  1.59813],
       [ 2.98863,  0.86173, -0.59616],
       [-0.78312,  2.20935, -2.22362],
       [-2.73208,  1.02071,  1.44702],
       [-0.36006, -1.82939, -0.72827]])
       
a[1:] += 0.05
print(a)

输出将是:

[[ 0.08778  0.99666  0.30648]
 [ 0.46688  2.75076  1.15135]
 [ 1.95494  0.96685 -0.21984]
 [-0.39512  1.78972 -1.19406]
 [-1.63572  1.06617  1.06221]
 [-0.1477  -0.72177 -0.30553]
 [ 0.66588  3.7495   1.64813]
 [ 3.03863  0.91173 -0.54616]
 [-0.73312  2.25935 -2.17362]
 [-2.68208  1.07071  1.49702]
 [-0.31006 -1.77939 -0.67827]]

b = a[1:] + 0.05 不是等价的,因为 b 不会有第一行 a