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2026-07-20 20:49:37 +02:00

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Python
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#!/usr/bin/env python3
# First time I use [[click]] ~ anagora.org/click, it looks cool like the other [[pallets project]], [[flask]], which we use in [[agora server]].
# https://click.palletsprojects.com/en/8.1.x/arguments/
# https://click.palletsprojects.com/en/8.1.x/options/
import click
import math
import sys
def get_prime_factors(n):
"""Computes the full prime factorization of n."""
factors = []
d = 2
temp = abs(n)
while d * d <= temp:
while temp % d == 0:
factors.append(d)
temp //= d
d += 1
if temp > 1:
factors.append(temp)
return factors
def get_factor_pairs(n):
"""Returns all proper factor pairs (a, b) such that a * b = n with a <= b."""
pairs = []
n_abs = abs(n)
for i in range(2, math.isqrt(n_abs) + 1):
if n_abs % i == 0:
pairs.append((i, n_abs // i))
return pairs
def get_proper_divisors(n):
"""Returns all proper divisors of n strictly between 1 and n."""
divs = set()
n_abs = abs(n)
for i in range(2, math.isqrt(n_abs) + 1):
if n_abs % i == 0:
divs.add(i)
divs.add(n_abs // i)
return sorted(list(divs))
def sieve_primes(n):
"""Generates all prime numbers up to n using the Sieve of Eratosthenes."""
if n < 2:
return []
sieve = [True] * (n + 1)
sieve[0] = sieve[1] = False
for i in range(2, math.isqrt(n) + 1):
if sieve[i]:
for j in range(i * i, n + 1, i):
sieve[j] = False
return [i for i, is_p in enumerate(sieve) if is_p]
def format_primes(primes, limit=50):
"""Formats a list of primes with wikilinks, capping output if too long."""
total = len(primes)
if total <= limit:
return ", ".join(f"[[{p}]]" for p in primes)
else:
shown = ", ".join(f"[[{p}]]" for p in primes[:limit])
return f"{shown}, ... ({total} total)"
class AgoraCmd(click.Command):
def format_help(self, ctx, formatter):
click.echo("""Usage:
- Visit anagora.org/primes to execute this file in the Agora of Flancia.
- Visit e.g. anagora.org/primes/17 to test if 17 is prime.
- In general visit anagora.org/foo, anagora.org/foo/bar to execute e.g. <bin/foo.py bar> from your garden.
""")
def __call__(self, *args, **kwargs):
try:
return super(AgoraCmd, self).__call__(
*args, standalone_mode=False, **kwargs)
except click.MissingParameter as exc:
exc.ctx = None
exc.show(file=sys.stdout)
click.echo()
try:
super(AgoraCmd, self).__call__(['--help'])
except SystemExit:
sys.exit(exc.exit_code)
@click.command(cls=AgoraCmd)
@click.argument('n', type=click.INT)
def prime(n):
"""Factors a number using prime decomposition and a [[Sieve of Eratosthenes]]."""
if n <= 1:
click.echo(f"[[{n}]] is neither prime nor composite.")
return
factors = get_prime_factors(n)
is_p = (len(factors) == 1)
if is_p:
click.echo(f"[[{n}]] is *prime*.")
else:
click.echo(f"[[{n}]] is *not prime* (composite). Want proof? :)")
factor_links = " * ".join(f"[[{f}]]" for f in factors)
click.echo(f"\nFull prime factorization: {factor_links}")
pairs = get_factor_pairs(n)
if pairs:
click.echo("\nFactor pairs:")
for a, b in pairs:
click.echo(f" [[{n}]] = [[{a}]] * [[{b}]]")
divs = get_proper_divisors(n)
if divs:
divs_str = ", ".join(f"[[{d}]]" for d in divs)
click.echo(f"\nProper divisors: {divs_str}")
primes = sieve_primes(n)
if primes:
click.echo(f"\nPrimes up to {n}: {format_primes(primes)}.")
if __name__ == '__main__':
prime()