python - shuffle vs permute numpy -

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what difference between numpy.random.shuffle(x) , numpy.random.permutation(x)?

i have read doc pages not understand if there difference between 2 when want randomly shuffle elements of array.

to more precise suppose have array x=[1,4,2,8].

if want generate random permutations of x, difference between shuffle(x) , permutation(x)?

np.random.permutation has 2 differences np.random.shuffle:

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

if x integer, randomly permute np.arange(x). if x array, make copy , shuffle elements randomly.

the source code might 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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