How can I make an object with an interface like a random number generator, but that actually generates a specified sequence?

Question

I'd like to construct an object that works like a random number generator, but generates numbers in a specified sequence.

# a random number generator
rng = lambda : np.random.randint(2,20)//2

# a non-random number generator
def nrng():
    numbers = np.arange(1,10.5,0.5)
    for i in range(len(numbers)):
        yield numbers[i]

for j in range(10):
    print('random number', rng())
    print('non-random number', nrng())

The issue with the code above that I cannot call nrng in the last line because it is a generator. I know that the most straightforward way to rewrite the code above is to simply loop over the non-random numbers instead of defining the generator. I would prefer getting the example above to work because I am working with a large chunk of code that include a function that accepts a random number generator as an argument, and I would like to add the functionality to pass non-random number sequences without rewriting the entire code.

EDIT: I see some confusion in the comments. I am aware that python's random number generators generate pseudo-random numbers. This post is about replacing a pseudo-random-number generator by a number generator that generates numbers from a non-random, user-specified sequence (e.g., a generator that generates the number sequence 1,1,2,2,1,0,1 if I want it to).

Answer 1

You can call next() with a generator or iterator as an argument to withdraw exactly one element from it. Saving the generator to a variable beforehand allows you to do this multiple times.

# make it a generator
def _rng():
    while True:
        yield np.random.randint(2,20)//2

# a non-random number generator
def _nrng():
    numbers = np.arange(1,10.5,0.5)
    for i in range(len(numbers)):
        yield numbers[i]

rng = _rng()
nrng = _nrng()
for j in range(10):
    print('random number', next(rng))
    print('non-random number', next(nrng))