Consistently create same random numpy array

Create your own instance of numpy.random.RandomState() with your chosen seed. Do not use numpy.random.seed() except to work around inflexible libraries that do not let you pass around your own RandomState instance.

[~]
|1> from numpy.random import RandomState

[~]
|2> prng = RandomState(1234567890)

[~]
|3> prng.randint(-1, 2, size=10)
array([ 1,  1, -1,  0,  0, -1,  1,  0, -1, -1])

[~]
|4> prng2 = RandomState(1234567890)

[~]
|5> prng2.randint(-1, 2, size=10)
array([ 1,  1, -1,  0,  0, -1,  1,  0, -1, -1])

Simply seed the random number generator with a fixed value, e.g.

numpy.random.seed(42)

This way, you'll always get the same random number sequence.

This function will seed the global default random number generator, and any call to a function in numpy.random will use and alter its state. This is fine for many simple use cases, but it's a form of global state with all the problems global state brings. For a cleaner solution, see Robert Kern's answer below.