Introduction

Fast PrimeNumbers generator which caches previous results across instances.
You usually don't need as many primes as the worst-case - eg for the included lcm (lowest common multiplier) function.

Also provides a very fast primesieve if you wish to pre-calculate a large number of primes.

Getting Started

Installation: pip install primegenerator

Main usage:

from primegenerator import PrimeNumbers
primes = PrimeNumbers()
for prime in primes:
    ... #do something
    if ... #beware this is an infinite iterator!
        break

Test if number is prime:

from primegenerator import PrimeNumbers
assert 5 in PrimeNumbers()
assert 9 not in PrimeNumbers()

Get a specific prime:

from primegenerator import PrimeNumbers
primes = PrimeNumbers(startat1=True)
assert primes[3] == 5
assert primes[3:5] == [5,7]

Preseed - if you know you need all primes up to n:

from primegenerator import PrimeNumbers
n = 100 #somebignumber
primes = PrimeNumbers.preseed(n)
for prime in primes:
    ... #do something
    if ... #beware this is still an infinite iterator and will keep going past the seed point!
        break

Lowest common multiplier:

from primegenerator import lcm
numbers = [2,3,4]
assert lcm(numbers) == 12
assert lcm(3,4,5) == 60

Sieve:

from primegenerator import primesieve
listofprimes = primesieve(maxprime)

Build and Test

Tests are written for pytest in /tests/test_*.py
pip -r tests/requirements.txt for additional imports required for some tests.
Tests are available on the ADO repository (see link below)

/dev contains some useful stuff for debugging, profiling and further development and is only available on the ADO repository (see link below)

Contribute

Code repository (ADO): https://dev.azure.com/MusicalNinjas/MikesMath/_git/primes
Homepage: https://dev.azure.com/MusicalNinjas/MikesMath

What's New?

v1.3.1

• Slicing supports negative step

v1.3.0

• Get a specific prime with primes[n] or primes[n:m]

v1.2.1

• test_wrapper improvements

v1.2.0

• n in PrimeNumbers() will test if n is prime

v1.1.0

• lcm will take multiple arguments and find lowest common multiplier. (Previously required a single list or tuple)

v1.0.0

• PrimeNumbers() infinite iterator supporting startat1, .preseed()
• lcm to find lowest common multiplier
• sieve to return a list of primes

Coming next...

Able to launch a parallel process to pre-calculate the next prime needed on a separate CPU core