列表上的动态嵌套循环答案

【问题标题】：Dynamic Nested Loops on Lists列表上的动态嵌套循环
【发布时间】：2016-10-16 07:09:33
【问题描述】：

我有以下代码来计算许多游戏的所有可能赔率组合。我想做以下事情

删除所有难看的嵌套循环。
允许动态游戏，即我不必一直创建匹配列表添加和添加条目到嵌套循环。（例如我想添加匹配 k）

代码如下；

import numpy as np

"""
Odds Predictions.
----------------------------------------
"""

bet_amount = 1.00

# Set up odds of all teams in groups, touple contains odds for coming in first place and second place.
match_a = [("RUS-W", 2.37), ("RUS-X", 3.20), ("RUS-L", 3.50)]
match_b = [("ROM-W", 3.30), ("ROM-X", 3.10), ("ROM-L", 2.50)]
match_c = [("FRA-W", 1.25), ("FRA-X", 6.00), ("FRA-L", 11.00)]
match_d = [("ENG-W", 1.57), ("ENG-X", 4.00), ("END-L", 7.00)]
match_e=  [("UKR-W", 1.57), ("UKR-X", 4.00), ("UKR-L", 7.00)]
match_f = [("GER-W", 1.57), ("GER-X", 4.33), ("GER-L", 6.50)]
match_g = [("ITA-W", 1.83), ("ITA-X", 3.50), ("ITA-L", 5.25)]
match_h = [("CZK-W", 4.75), ("CZK-X", 3.50), ("CZK-L", 1.90)]
match_i = [("SPA-W", 1.40), ("SPA-X", 4.75), ("SPA-L", 10.00)]
match_j = [("BEL-W", 1.72), ("BEL-X", 3.80), ("BEL-L", 5.50)]

totals = []
total_rank = []
count = 0

print 'Computing Combinations'

for mat_a in match_a:
  for mat_b in match_b:
    for mat_c in match_c:
      for mat_d in match_d:
        for mat_e in match_e:
          for mat_f in match_f:
            for mat_g in match_g:
              for mat_h in match_h:
                for mat_i in match_i:
                  for mat_j in match_j:

                    entry = '%s, %s, %s, %s, %s, %s, %s, %s, %s, %s,' % (mat_a[0] , mat_b[0] , mat_c[0] , mat_d[0] , mat_e[0] , mat_f[0], mat_g[0] , mat_h[0] , mat_i[0] , mat_j[0])
                    rank = mat_a[1] * mat_b[1] * mat_c[1] * mat_d[1] * mat_e[1] * mat_f[1]* mat_g[1] * mat_h[1] * mat_i[1] * mat_j[1]

                    totals.append([entry, rank])
                    total_rank.append(totals)

                    count += 1

print 'Total Combinations : %d ' % count
print 'Sorting Combinations'

totals = sorted(totals,key=lambda x: x[1])

print 'Bet Amount : %f' % bet_amount

for count, total in enumerate(totals):
  if count < 100:
    print ' %s  ->  %s' % (total[0], total[1] * bet_amount)
  else:
    break;

【问题讨论】：

标签： python list loops numpy nested

【解决方案1】：

你应该看看itertools.product。此外，您的 total_rank 列表似乎毫无意义（请注意，它会一遍又一遍地包含对相同列表的许多引用）并且 count 只是结果的 len列表。

import itertools, operator
matches = [match_a, match_b, match_c, match_d, match_e, match_f, match_g, match_h, match_i, match_j]

for mat_x in itertools.product(*matches):
    entry = ", ".join(x[0] for x in mat_x)
    rank = reduce(operator.mul, (x[1] for x in mat_x))
    totals.append([entry, rank])

print 'Total Combinations : %d ' % len(totals)

你甚至可以把它变成一个列表理解：

totals = [(", ".join(x[0] for x in mat_x), reduce(operator.mul, (x[1] for x in mat_x))) 
          for mat_x in itertools.product(*matches)]

【讨论】：