假设我有一个列表L。如何获得一个遍历K组所有分区的迭代器?
例如:L = [ 2,3,5,7,11, 13],K = 3
所有3组分区的列表:
[ [ 2 ], [ 3, 5], [ 7,11,13] ]
[ [ 2,3,5 ], [ 7, 11], [ 13] ]
[ [ 3, 11 ], [ 5, 7], [ 2, 13] ]
[ [ 3 ], [ 11 ], [ 5, 7, 2, 13] ]
etc...
=== 更新 ===
我正在解决一个问题,看起来已经有效了,所以我将只是复制粘贴它。
# -*- coding: utf-8 -*-
import itertools
# return ( list1 - list0 )
def l1_sub_l0( l1, l0 ) :
"""Substract two lists"""
#
copy_l1 = list( l1 )
copy_l0 = list( l0 )
#
for xx in l0 :
#
if copy_l1.count( xx ) > 0 :
#
copy_l1.remove( xx )
copy_l0.remove( xx )
#
return [ copy_l1, copy_l0 ]
#
def gen_group_len( n, k ) :
"""Generate all possible group sizes"""
# avoid doubles
stop_list = []
#
for t in itertools.combinations_with_replacement( xrange( 1, n - 1 ), k - 1 ) :
#
last_n = n - sum( t )
# valid group size
if last_n >= 1 :
res = tuple( sorted( t + ( last_n, ) ) )
#
if res not in stop_list :
yield res
stop_list.append( res )
# group_len = (1, 1, 3)
def gen( group_len, my_list ) :
"""Generate all possible partitions of all possible group sizes"""
#
if len( group_len ) == 1 :
yield ( tuple( my_list ), )
#
else :
# need for a stop list if 2 groups of same size
stop_list = []
#
for t in itertools.combinations( my_list, group_len[ 0 ] ) :
#
reduced_list = l1_sub_l0( my_list, t )[ 0 ]
#
for t2 in gen( group_len[ 1: ], reduced_list ) :
#
tmp = set( ( t, t2[ 0 ] ) )
#
if tmp not in stop_list :
yield ( t, ) + t2
# avoid doing same thing twice
if group_len[ 1 ] == group_len[ 0 ] :
stop_list.append( tmp )
#
my_list = [ 3,5,7,11,13 ]
n = len( my_list )
k = 3
#
group_len_list = list( gen_group_len( n, k ) )
print "for %i elements, %i configurations of group sizes" % ( n, len( group_len_list ) )
print group_len_list
#
for group_len in group_len_list :
#
print "group sizes", group_len
#
for x in gen( group_len, my_list ) :
print x
#
print "==="
输出:
for 5 elements, 2 configurations of group sizes
[(1, 1, 3), (1, 2, 2)]
group sizes (1, 1, 3)
((3,), (5,), (7, 11, 13))
((3,), (7,), (5, 11, 13))
((3,), (11,), (5, 7, 13))
((3,), (13,), (5, 7, 11))
((5,), (7,), (3, 11, 13))
((5,), (11,), (3, 7, 13))
((5,), (13,), (3, 7, 11))
((7,), (11,), (3, 5, 13))
((7,), (13,), (3, 5, 11))
((11,), (13,), (3, 5, 7))
===
group sizes (1, 2, 2)
((3,), (5, 7), (11, 13))
((3,), (5, 11), (7, 13))
((3,), (5, 13), (7, 11))
((5,), (3, 7), (11, 13))
((5,), (3, 11), (7, 13))
((5,), (3, 13), (7, 11))
((7,), (3, 5), (11, 13))
((7,), (3, 11), (5, 13))
((7,), (3, 13), (5, 11))
((11,), (3, 5), (7, 13))
((11,), (3, 7), (5, 13))
((11,), (3, 13), (5, 7))
((13,), (3, 5), (7, 11))
((13,), (3, 7), (5, 11))
((13,), (3, 11), (5, 7))
===
((3,), (5,), (7, 11, 13))
和((7, 11, 13)), (3,), (5,))
是相同的吗? - pylang