# brainpy.math.random.random_integers#

brainpy.math.random.random_integers(low, high=None, size=None, key=None)[source]#

Random integers of type np.int_ between low and high, inclusive.

Return random integers of type np.int_ from the “discrete uniform” distribution in the closed interval [low, high]. If high is None (the default), then results are from [1, low]. The np.int_ type translates to the C long integer type and its precision is platform dependent.

Parameters:
• low (int) – Lowest (signed) integer to be drawn from the distribution (unless high=None, in which case this parameter is the highest such integer).

• high (int, optional) – If provided, the largest (signed) integer to be drawn from the distribution (see above for behavior if high=None).

• 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.

Returns:

outsize-shaped array of random integers from the appropriate distribution, or a single such random int if size not provided.

Return type:

int or ndarray of ints

See also

randint

Similar to random_integers, only for the half-open interval [low, high), and 0 is the lowest value if high is omitted.

Notes

To sample from N evenly spaced floating-point numbers between a and b, use:

a + (b - a) * (bm.random.random_integers(N) - 1) / (N - 1.)


Examples

>>> import brainpy.math as bm
>>> bm.random.random_integers(5)
4 # random
>>> type(bm.random.random_integers(5))
<class 'numpy.int64'>
>>> bm.random.random_integers(5, size=(3,2))
array([[5, 4], # random
[3, 3],
[4, 5]])


Choose five random numbers from the set of five evenly-spaced numbers between 0 and 2.5, inclusive (i.e., from the set $${0, 5/8, 10/8, 15/8, 20/8}$$):

>>> 2.5 * (bm.random.random_integers(5, size=(5,)) - 1) / 4.
array([ 0.625,  1.25 ,  0.625,  0.625,  2.5  ]) # random


Roll two six sided dice 1000 times and sum the results:

>>> d1 = bm.random.random_integers(1, 6, 1000)
>>> d2 = bm.random.random_integers(1, 6, 1000)
>>> dsums = d1 + d2


Display results as a histogram:

>>> import matplotlib.pyplot as plt
>>> count, bins, ignored = plt.hist(dsums, 11, density=True)
>>> plt.show()