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  • #3746
Closed
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Issue created May 17, 2022 by 4atj@4atj

Fractions are slow in PyPy

This is why the Markov decision process in pyperformance is slower in PyPy.

from time import perf_counter
from fractions import Fraction

def primes(n): # returns first n primes
    primes = [2]
    i=3
    while len(primes)<n:
        if all(i%p for p in primes):
            primes.append(i)
        i+=2
    return primes

T=1000
N=1000

a = [Fraction(i)/Fraction(p) for i,p in enumerate(primes(N))] # Worst case CPython: 3.60 secs | PyPy: 142.1 secs
t = perf_counter()
for _ in range(T): sum(a)
print(perf_counter()-t)

a = [Fraction(i)/Fraction(N) for i in range(N)] # Good case CPython: 1.23 secs | PyPy: 0.10 secs
t = perf_counter()
for _ in range(T): sum(a)
print(perf_counter()-t)
Edited May 17, 2022 by 4atj
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