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# numpy.random.RandomState.choice

method

random.RandomState.choice(a, size=None, replace=True, p=None)

  Generates a random sample from a given 1-D array

  Note

  New code should use the `choice` method of a `Generator` instance instead; please see the Quick start.

  Warning

  This function uses the C-long dtype, which is 32bit on windows and otherwise 64bit on 64bit platforms (and 32bit on 32bit ones). Since NumPy 2.0, NumPy’s default integer is 32bit on 32bit platforms and 64bit on 64bit platforms.

  Parameters:
    a 1-D array-like or int

      If an ndarray, a random sample is generated from its elements. If an int, the random sample is generated as if it were `np.arange(a)`

    size int or tuple of ints, optional

      Output shape. If the given shape is, e.g., `(m, n, k)`, then `m * n * k` samples are drawn. Default is None, in which case a single value is returned.

    replace boolean, optional

      Whether the sample is with or without replacement. Default is True, meaning that a value of `a` can be selected multiple times.

    p 1-D array-like, optional

      The probabilities associated with each entry in a. If not given, the sample assumes a uniform distribution over all entries in `a`.

  Returns:
    samples single item or ndarray

      The generated random samples

  Raises:
    ValueError

      If a is an int and less than zero, if a or p are not 1-dimensional, if a is an array-like of size 0, if p is not a vector of probabilities, if a and p have different lengths, or if replace=False and the sample size is greater than the population size

  See also

  `randint`, `shuffle`, `permutation`
  `random.Generator.choice`

    which should be used in new code

  Notes

  Setting user-specified probabilities through `p` uses a more general but less efficient sampler than the default. The general sampler produces a different sample than the optimized sampler even if each element of `p` is 1 / len(a).

  Sampling random rows from a 2-D array is not possible with this function, but is possible with Generator.choice through its `axis` keyword.

  Examples

  Generate a uniform random sample from np.arange(5) of size 3:

      >>> np.random.choice(5, 3)
      array([0, 3, 4]) # random
      >>> #This is equivalent to np.random.randint(0,5,3)

  Generate a non-uniform random sample from np.arange(5) of size 3:

      >>> np.random.choice(5, 3, p=[0.1, 0, 0.3, 0.6, 0])
      array([3, 3, 0]) # random

  Generate a uniform random sample from np.arange(5) of size 3 without replacement:

      >>> np.random.choice(5, 3, replace=False)
      array([3,1,0]) # random
      >>> #This is equivalent to np.random.permutation(np.arange(5))[:3]

  Generate a non-uniform random sample from np.arange(5) of size 3 without replacement:

      >>> np.random.choice(5, 3, replace=False, p=[0.1, 0, 0.3, 0.6, 0])
      array([2, 3, 0]) # random

  Any of the above can be repeated with an arbitrary array-like instead of just integers. For instance:

      >>> aa_milne_arr = ['pooh', 'rabbit', 'piglet', 'Christopher']
      >>> np.random.choice(aa_milne_arr, 5, p=[0.5, 0.1, 0.1, 0.3])
      array(['pooh', 'pooh', 'pooh', 'Christopher', 'piglet'], # random
            dtype='<U11')