Pseudo-random numbers/PCG32: Difference between revisions
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→{{header|Python}}: Add generator version. |
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=={{header|Python}}== |
=={{header|Python}}== |
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===Python: As class=== |
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<lang python>mask64 = (1 << 64) - 1 |
<lang python>mask64 = (1 << 64) - 1 |
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mask32 = (1 << 32) - 1 |
mask32 = (1 << 32) - 1 |
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for i in range(100_000): |
for i in range(100_000): |
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hist[int(random_gen.next_float() *5)] += 1 |
hist[int(random_gen.next_float() *5)] += 1 |
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print(hist)</lang> |
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{{out}} |
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<pre>2707161783 |
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2068313097 |
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3122475824 |
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2211639955 |
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3215226955 |
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{0: 20049, 1: 20022, 2: 20115, 3: 19809, 4: 20005}</pre> |
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===Python: As generator=== |
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(Must divide int by 1 << 32 to get float values). |
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<lang python>mask64 = (1 << 64) - 1 |
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mask32 = (1 << 32) - 1 |
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CONST = 6364136223846793005 |
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def pcg32(seed_state=None, seed_sequence=None): |
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def next_int(): |
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"return random 32 bit unsigned int" |
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nonlocal state, inc |
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state, xorshifted, rot = (((state * CONST) + inc) & mask64, |
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(((state >> 18) ^ state) >> 27) & mask32, |
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(state >> 59) & mask32) |
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answer = (((xorshifted >> rot) | (xorshifted << ((-rot) & 31))) |
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& mask32) |
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return answer |
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# Seed |
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state = inc = 0 |
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if all(type(x) == int for x in (seed_state, seed_sequence)): |
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inc = ((seed_sequence << 1) | 1) & mask64 |
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next_int() |
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state += seed_state |
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next_int() |
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while True: |
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yield next_int() |
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if __name__ == '__main__': |
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from itertools import islice |
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for i in islice(pcg32(42, 54), 5): |
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print(i) |
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hist = {i:0 for i in range(5)} |
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for i in islice(pcg32(987654321, 1), 100_000): |
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hist[int(i / (1 << 32) * 5)] += 1 |
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print(hist)</lang> |
print(hist)</lang> |
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