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]
>>>
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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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