This notebook was prepared by [Thunder Shiviah](https://github.com/ThunderShiviah). Source and license info is on [GitHub](https://github.com/ThunderShiviah/code_guild).
Primes are numbers which are only divisible by 1 and themselves.
5 is a prime since it can only be divided by itself and 1. 9 is not a prime since it can be divided by 3 (3*3 = 9). 1 is not a prime for reasons that only mathematicians care about.
To check if a number is prime, we can implement a basic algorithm, namely: check if a given number can be divided by any numbers smaller than the given number (note: you really only need to test numbers up to the square root of a given number, but it doesn't really matter for this assignment).
In [98]:
def list_primes(n):
primes = []
for p in range(2, n + 1): # we add a '+ 1' to be inclusive.
for num in range(2, p):
if p % num == 0:
break
else:
primes.append(p)
return primes
In [99]:
list_primes(6)
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In [100]:
%%writefile test_list_primes.py
from nose.tools import assert_equal
class Test_list_primes(object):
def test_list_primes(self):
assert_equal(list_primes(1), [])
assert_equal(list_primes(2), [2])
assert_equal(list_primes(7), [2, 3, 5, 7])
assert_equal(list_primes(9), list_primes(7))
print('Success: test_list_primes')
def main():
test = Test_list_primes()
test.test_list_primes()
if __name__ == '__main__':
main()
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%run -i test_list_primes.py
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