时间戳

首页 > 解决方案 > Using dict values to count iterations over a list to insert

python - Using dict values to count iterations over a list to insert

问题描述

import random
from itertools import repeat

races_per_season = {
    '2015' : "19",
    '2016' : "21",
    '20116' : "21",
    '2017' : "20",
    '2018' : "21",
    '2019' : "21",
    '2020' : "17",
    '2021' : "16"
}

tmp_list = list(repeat(random.sample(range(80),10), 156))
total_races = 0
for k,v in races_per_season.items(): 
    while total_races < int(v):
        tmp_list[total_races].insert(1, k)
        total_races += 1
        break # inserting breaks here and below, somewhat works, but only gives me the first year throughout the list
    break


for x in tmp_list:
    print(x)

I am trying to use the dict values to iterate over a list of list and insert the key into the list at index 1. However, no matter how I try, it seems to iterate and insert all keys into the list then moves on to the next...

This is the result I am seeing.... however by adding the breaks above, this continues throughout the list of 156 lists.. and doesn't change at list 19

[[29, '2015', 56, 39, 31, 25, 37, 5, 16, 8, 73],
 [29, '2015',  56, 39, 31, 25, 37, 5, 16, 8, 73],
 [29, '2015',  56, 39, 31, 25, 37, 5, 16, 8, 73],
 [29, '2015', 56, 39, 31, 25, 37, 5, 16, 8, 73]]

but my desired result is the following.

[[29, '2015', 56, 39, 31, 25, 37, 5, 16, 8, 73],
 [29, '2015', 56, 39, 31, 25, 37, 5, 16, 8, 73],
 [29, '2015', 56, 39, 31, 25, 37, 5, 16, 8, 73],
 [29, '2015', 56, 39, 31, 25, 37, 5, 16, 8, 73],
 [29, '2015', 56, 39, 31, 25, 37, 5, 16, 8, 73],
 [29, '2015', 56, 39, 31, 25, 37, 5, 16, 8, 73]...

and continuing with '2015' 19 times, then inserting '2016' into the following 21 etc.. When I just print out the k,v pairs it works as I want it to, but I can't somehow convert that into a list. All values in the dict sum to the value of the len(tmp_list) 156

ANY help would be more than appreciated. Thanks

标签： pythonlistdictionary

解决方案

你可以试试这个，似乎至少对我有用。

import random
from itertools import repeat

races_per_season = {
    '2015' : "19",
    '2016' : "21",
    '20116' : "21",
    '2017' : "20",
    '2018' : "21",
    '2019' : "21",
    '2020' : "17",
    '2021' : "16"
}

tmp_list = list(repeat(random.sample(range(80), 10), 156))

seasons = [season for season, races in races_per_season.items()
           for i in range(int(races))]

tmp_list = [[L[0], seasons[i], *L[1:]] for i, L in enumerate(tmp_list)]

for x in tmp_list:
    print(x)

结果：

[44, '2015', 18, 33, 30, 54, 22, 53, 19, 4, 68]
...repeated 18 times
[44, '2016', 18, 33, 30, 54, 22, 53, 19, 4, 68]
...repeated 20 times
...

解释

在上述方法的第一部分，我们使用两个list推导来构建一个years变量。第一个推导遍历字典中的键值对，第二个推导遍历0...n-1每个键的值中的所有数字——例如，我们有键 '2015' n=19。

解释以下使用的语法：

[L[0], seasons[i], *L[1:]]

这基本上说：

  1. 创建一个新列表，其中的第一个元素L是 中的子列表tmp_list
  2. 添加我们正在迭代的季节作为第二个元素
  3. [1:]说，给我除了第一个元素之外的子列表中的所有元素。星*号运算符再次解包该结果，因此我们不会在每个列表中都有一个列表。

推荐阅读