Question

我有以下代码：

import numpy as np

a = np.array([["value1", "value2", 3, "value4", "value5"],
             ["value1", "value2", -10, "value4", "value5"],
             ["value1", "value2", 31, "value4", "value5"],
             ["value1", "value2", 5, "value4", "value5"],
             ["value1", "value2", 3, "value4", "value5"]])

print("Default")
print(a)

a = a[a[:, 2].argsort()]

print()
print("Sorted:")
print(a)

这导致以下输出：

Sorted:
[['value1' 'value2' '-10' 'value4' 'value5']
 ['value1' 'value2' '3' 'value4' 'value5']
 ['value1' 'value2' '3' 'value4' 'value5']
 ['value1' 'value2' '31' 'value4' 'value5']
 ['value1' 'value2' '5' 'value4' 'value5']]

但我正在寻找的功能是输出这个：

Sorted:
[['value1' 'value2' '-10' 'value4' 'value5']
 ['value1' 'value2' '3' 'value4' 'value5']
 ['value1' 'value2' '3' 'value4' 'value5']
 ['value1' 'value2' '5' 'value4' 'value5']
 ['value1' 'value2' '31' 'value4' 'value5']]

当我将31值更改为51时，它会正确输出。所以numpy基本上是对数字的第一个字符进行排序。但我找不到如何对整个数字进行排序。

Answer 1

如评论中所述，您要排序的值是字符串。变化

a = a[a[:, 2].argsort()]

到

a = a[a[:, 2].astype(np.int).argsort()]

因此将它们作为整数进行比较。

Answer 2

您必须将第三列转换为整数。

看这里：

a = ['5']
b = ['31']
if a[0] > b[0]:
    print("{} is bigger than {}".format(a[0], b[0]))

Out[0]: 5 is bigger than 31

a = int(a[0])
b = int(b[0])
if b > a:
    print("{} is bigger than {}".format(b, a)) 

Out[1]: 31 is bigger than 5

出于这个原因，请按照：

 import numpy as np

 a = np.array('your array')
 a = a[a[:, 2].astype(np.int).argsort()]

Numpy argsort，排序第一个数字

2 个答案: