Primes

{article Examples__Python 3.4 }{title} {text}{/article}

Python- Sieve of Eratosthenes

 


Example 1

>>> def pgen(n): # Sieve of Eratosthenes generator by Dan Salmonsen
yield 2
np = set()
for q in xrange(3, n+1, 2):
if q not in np:
yield q
np.update(range(q*q, n+1, q+q))


>>> list(pgen(100))
[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]
>>> list(pgen(30))
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29]

 


 

Example 2

>>> def primes(n): # Sieve of Eratosthenes generator by Dan Salmonsen
yield 2
np = set()
for q in xrange(3, n+1, 2):
if q not in np:
yield q
np.update(range(q*q, n+1, q+q))


>>> list(primes(100))
[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]
>>>

 


Example 3

>>> nums = range(2, 50)
>>> for i in range(2, 8):
nums = filter(lambda x: x == i or x % i, nums)


>>> print nums
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47]

>>> list(nums)
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47]
>>>

{source}
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<pre class="brush:py;">
Example 1

>>> def pgen(n): # Sieve of Eratosthenes generator by Dan Salmonsen
    yield 2
    np = set()
    for q in xrange(3, n+1, 2):
        if q not in np:
            yield q
            np.update(range(q*q, n+1, q+q))


>>> list(pgen(100))
[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]
>>> list(pgen(30))
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29]





Example 2

>>> def primes(n): # Sieve of Eratosthenes generator by Dan Salmonsen
    yield 2
    np = set()
    for q in xrange(3, n+1, 2):
        if q not in np:
            yield q
            np.update(range(q*q, n+1, q+q))


>>> list(primes(100))
[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]
>>>



Example 3

>>> nums = range(2, 50)
>>> for i in range(2, 8):
    nums = filter(lambda x: x == i or x % i, nums)


>>> print nums
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47]

>>> list(nums)
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47]
>>>

</pre>

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