generating uniform distribution of integeres with python

Question

I tried to generate an uniform distribution of random integeres on a given interval (it's unimportant whether it contains its upper limit or not) with python. I used the next snippet of code to do so and plot the result:

import numpy as np
import matplotlib.pyplot as plt
from random import randint

propsedPython = np.random.randint(0,32767,8388602)%2048
propsedPythonNoMod = np.random.randint(0,2048,8388602)
propsedPythonNoModIntegers = np.random.random_integers(0,2048,8388602)
propsedPythonNoModRandInt = np.empty(8388602)
for i in range(8388602):
    propsedPythonNoModRandInt[i] = randint(0,2048)

plt.figure(figsize=[16,10])
plt.title(r'distribution $\rho_{prop}$ off all the python simulated proposed indices')
plt.xlabel(r'indices')
plt.ylabel(r'$\rho_{prop}$')
plt.yscale('log')
plt.hist(propsedPython,bins=1000,histtype='step',label=r'np.random.randint(0,32767,8388602)%2048')
plt.hist(propsedPythonNoMod,bins=1000,histtype='step',label=r'np.random.randint(0,2048,8388602')
plt.hist(propsedPythonNoModIntegers,bins=1000,histtype='step',label=r'np.random.random_integers(0,2048,8388602)')
plt.hist(propsedPythonNoModRandInt,bins=1000,histtype='step',label=r'for i in range(8388602):propsedPythonNoModRandInt[i] = randint(0,2048)')
plt.legend(loc=0)

The resulting plot is: Could somebody point me in the right direction why these spikes appear in al the different cases and or gives some advice which routine to use to got uniformly distributed random integers?

Thanks a lot!

Answer 1

Mmm...

I used new NumPy rng facility, and graph looks ok to me.

Code

import numpy as np
import matplotlib.pyplot as plt

rng = np.random.default_rng()

N = 1024*500

hist = np.zeros(2048, dtype=np.int32)

q = rng.integers(0, 2048, dtype=np.int32, size=N, endpoint=False)

for k in range(0, N):
    hist[q[k]] += 1

x = np.arange(0, 2048, dtype=np.int32)

fig, ax = plt.subplots()
ax.stem(x, hist, markerfmt=' ')
plt.show()

and graph