python - 使用 NumPy 按元素长度对字符串数组进行排序

Question

我想使用 numpy 按元素的长度对字符串数组进行排序。

>>> arr = ["year","month","eye","i","stream","key","house"]
>>> x = np.sort(arr, axis=-1, kind='mergesort')
>>> print(x)
['eye' 'house' 'i' 'key' 'month' 'stream' 'year']

但它按字母数字顺序对它们进行排序。我如何使用 numpy 按长度对它们进行排序？

Answer 1

添加一个包含字符串长度的辅助数组，然后使用 numpy 的 argsort 为您提供根据这些长度排序的索引。使用这些索引对原始数据进行索引:

import numpy as np
arr = np.array(["year","month","eye","i","stream","key","house"])  # np-array needed for later indexing
arr_ = map(lambda x: len(x), arr)  # remark: py3 would work different here
x = arr[np.argsort(arr_)]
print(x)