随机播放vs置换numpy [英] shuffle vs permute numpy

问题描述

numpy.random.shuffle(x)和numpy.random.permutation(x)有什么区别?

我已经阅读了文档页面，但是当我只想随机地对数组元素进行随机排列时，我不明白两者之间是否有任何区别.

I have read the doc pages but I could not understand if there was any difference between the two when I just want to randomly shuffle the elements of an array.

更准确地说，假设我有一个数组x=[1,4,2,8].

To be more precise suppose I have an array x=[1,4,2,8].

如果我想生成x的随机排列，那么shuffle(x)和permutation(x)有什么区别?

If I want to generate random permutations of x, then what is the difference between shuffle(x) and permutation(x)?

推荐答案

np.random.permutation与np.random.shuffle有两个区别:

• 如果传递了一个数组，它将返回该数组的改组的副本； np.random.shuffle将数组按顺序随机播放
• 如果传递整数，它将返回经过改组的范围，即np.random.shuffle(np.arange(n))

• if passed an array, it will return a shuffled copy of the array; np.random.shuffle shuffles the array inplace
• if passed an integer, it will return a shuffled range i.e. np.random.shuffle(np.arange(n))

如果x是整数，则随机置换np.arange(x).如果x是一个数组，请复制并随机洗净元素.

If x is an integer, randomly permute np.arange(x). If x is an array, make a copy and shuffle the elements randomly.

源代码可能有助于理解这一点:

The source code might help to understand this:

3280        def permutation(self, object x):
...
3307            if isinstance(x, (int, np.integer)):
3308                arr = np.arange(x)
3309            else:
3310                arr = np.array(x)
3311            self.shuffle(arr)
3312            return arr

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