PyKids/find_primes.py at master · git4robot/PyKids · GitHub

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'''A module to finds all kinds of primes. Version -- 2.5.5(at python 3+)'''
from math import sqrt
import numpy
from time import time
def is_prime(n):
    for i in range(2,int(sqrt(n)+1)):
        if n % i == 0:
            return False
    return True

def sieve_primes_Eratosthenes(n):
    sieve = numpy.ones(int(n/2), dtype=numpy.bool)
    limit = int(sqrt(n)) + 1

    for i in range(3, limit, 2):
        if sieve[int(i/2)]:
            sieve[int(i*i/2) :: i] = False

    prime_indexes = numpy.nonzero(sieve)[0][1::]
    primes = 2 * prime_indexes.astype(numpy.int32) + 1
    return primes

'''Before this string, the def don't work ----- After this string, the def can work'''
def find_twins(n):
    primes_n = []
    primes_n = sieve_primes_Eratosthenes(n)
    #孪生素数
    twin_primes = {}
    for ix,xp in enumerate(primes_n):
        if ix == len(primes_n) - 1:
            break
        new_xp = xp + 2
        if new_xp == primes_n[ix+1]:
            twin_primes[xp] = primes_n[ix+1]

    print("孪生素数:",twin_primes)

def find_reverse(n):
    primes_n = []
    primes_n = sieve_primes_Eratosthenes(n)
    #可逆素数
    reverse_primes = {}
    for ix,xp in enumerate(primes_n):
        reverse_num = int(str(xp)[::-1])
        if is_prime(reverse_num):
            reverse_primes[xp] = reverse_num

    print("可逆素数：",reverse_primes)

def find_palindromes(n):
    primes_n = []
    primes_n = sieve_primes_Eratosthenes(n)
    #回文素数
    palin_primes = {}
    for ix,xp in enumerate(primes_n):
        palin_num = int(str(xp)[::-1])
        if is_prime(palin_num) and palin_num == xp and xp > 10:
            palin_primes[xp] = palin_num

    print("回文素数：")
    for i in palin_primes:
        print(i)

def find_square_palindromes(n):
    primes_n = []
    primes_n = sieve_primes_Eratosthenes(n)
    #平方回文素数
    primes = {}
    for ix,xp in enumerate(primes_n):
        squares = xp**2
        palin = str(squares)[::-1]
        if palin == str(squares) and xp > 10:
            primes[xp] = xp

    print("平方回文素数：",)
    for i in primes:
        print(i,i**2)

def _test():
    start_tm = time()
    find_twins(5000)
    find_reverse(5000)
    find_palindromes(7500)
    find_square_palindromes(10000000)
    print("耗时：%f" % (time() - start_tm))

if __name__ == '__main__':
    _test()