onlyforbopi
1/30/2018 - 12:42 PM

## Python.Math.Itertools.Permutations.Combinations

Python.Math.Permutations.Combinations #python #Python #permutations #combinations #itertools #PythonModules

PERMUTATIONS AND COMBINATIONS - SORT

``````# -*- coding: utf-8 -*-
"""
Created on Fri Mar 31 09:49:49 2017

@author: P.Doulgeridis
"""

import itertools

def permutations(iterable, r=None):
# permutations('ABCD', 2) --> AB AC AD BA BC BD CA CB CD DA DB DC
# permutations(range(3)) --> 012 021 102 120 201 210
pool = tuple(iterable)
n = len(pool)
r = n if r is None else r
if r > n:
print("Combination length required longer than populace")
return
indices = list(range(n))
cycles = list(range(n, n-r, -1))
yield tuple(pool[i] for i in indices[:r])
while n:
for i in reversed(range(r)):
cycles[i] -= 1
if cycles[i] == 0:
indices[i:] = indices[i+1:] + indices[i:i+1]
cycles[i] = n - i
else:
j = cycles[i]
indices[i], indices[-j] = indices[-j], indices[i]
yield tuple(pool[i] for i in indices[:r])
break
else:
return

def permutations2(iterable, r=None):
pool = tuple(iterable)
n = len(pool)
r = n if r is None else r
for indices in product(range(n), repeat=r):
if len(set(indices)) == r:
yield tuple(pool[i] for i in indices)

a = [ 1, 2, 3, 7, "the" ]
c = [ 5, 6, 8, 9, "ifthen" ]
b = '4567'

# print(list(permutations(b, 3)))
# print(list(permutations(a, 5)))
# print(list(permutations(a, 4)))

# Permutation (Order matters)
#print (list(itertools.permutations(a, 3)))

# Combination (Order does not matter)
#print (list(itertools.combinations(a, 3)))

# Cartesian product (with several iterables - combine each with each one by one)
#print (list(itertools.product(a, c)))

# Cartesian product (with one iterable by itself, repeat factor)
#print (list(itertools.product(a, repeat=4)))

def permutation_generate(input, slots=2):
try:
import itertools
except ImportError:
return([],"ImportError: Itertools")

output_list = []
count = 0
calc = list(itertools.permutations(input, slots))
count = len(calc)
return [count, calc]

def combination_generate(input, slots=2):
try:
import itertools
except ImportError:
return([],"ImportError: Itertools")

output_list = []
count = 0
calc = list(itertools.combinations(input, slots))
count = len(calc)
return [count, calc]

def combi_repl_generate(input, slots=2):

checks = True

try:
import itertools
except ImportError:
return([],"ImportError: Itertools")

output_list = []
count = 0
calc = list(itertools.combinations_with_replacement(input, slots))
count = len(calc)
return [count, calc]

def cartesian_prod_generate(input1, input2):
try:
import itertools
except ImportError:
return([],"ImportError: Itertools")

output_list = []
count = 0
calc = list(itertools.product(a, c))
count = len(calc)

return [count, calc]

def cartesian_prod_repeat(input1, integer):
try:
import itertools
except ImportError:
return([],"ImportError: Itertools")

output_list = []
count = 0
calc = list(itertools.product(a, repeat=integer))
count = len(calc)

return [count, calc]

#print (permutation_generate(a, 4))
# print (combination_generate(a, 3))
# print (combi_repl_generate(a, 3))
#print (cartesian_prod_generate(a, c))
#print (cartesian_prod_repeat(c, 2))``````