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This module returns all the prime numbers strictly less than n. For this code to print out all of the primes n inclusive, in the range, n+1 must be substituted for n.

Python, 1 line
1
primeList = lambda n: set([i for i in range(2,n)]) ^ set([i for i in range(2,n) for x in range(2,int(i**0.5)+1) if i%x == 0])

Example:

primeList(1000) returns:

{2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997}

6 comments

Alexander James Wallar (author) 10 years, 1 month ago  # | flag

def isprime(n): for i in range(2,int(n**0.5)+1): if n%i == 0: return False return True

def isprime(n): for i in range(2,int(n**0.5)+1): if n%i == 0: return False return True

Alexander James Wallar (author) 10 years, 1 month ago  # | flag
def isprime(n):
for i in range(2,int(n**0.5)+1):
    if n%i == 0:
        return False
return True
def primeList(n):
    return list(filter(isprime,range(2,n)))
Seung-jin Kim 10 years ago  # | flag

Let's make one line shorter :-) primeList = lambda n : set([i for i in range(2,n)]) ^ set([i for i in range(2,n) for x in range(2,int(i**0.5)+1) if i%x == 0])

Seung-jin Kim, What does lambda n mean, and where does n get defined?

Ohhhh, That is awesome. I didn't know that you could define things in Python like that. That is really cool. It is like a 1 line function. Thanks a ton!

  • Alex

Thank You, Seung-jin Kim.

I have implemented your suggestion.