使用Python按属性值排序JSON

Question

我有以下JSON文件

{
   "modifyDate": 1463899037000,
   "champions": [
      {
         "id": 40,
         "stats": {
            "totalDeathsPerSession": 60,
            "totalSessionsPlayed": 18,
            "totalDamageTaken": 246343,
            "totalQuadraKills": 0,
            "totalTripleKills": 0,
            "totalMinionKills": 272,
            "maxChampionsKilled": 3,
            "totalDoubleKills": 0,
            "totalPhysicalDamageDealt": 121345,
            "totalChampionKills": 11,
            "totalAssists": 271,
            "mostChampionKillsPerSession": 3,
            "totalDamageDealt": 238803,
            "totalFirstBlood": 0,
            "totalSessionsLost": 7,
            "totalSessionsWon": 11,
            "totalMagicDamageDealt": 113241,
            "totalGoldEarned": 176088,
            "totalPentaKills": 0,
            "totalTurretsKilled": 10,
            "mostSpellsCast": 0,
            "maxNumDeaths": 9,
            "totalUnrealKills": 0
         }
      },
      {
         "id": 111,
         "stats": {
            "totalDeathsPerSession": 20,
            "totalSessionsPlayed": 4,
            "totalDamageTaken": 60371,
            "totalQuadraKills": 0,
            "totalTripleKills": 0,
            "totalMinionKills": 247,
            "maxChampionsKilled": 3,
            "totalDoubleKills": 0,
            "totalPhysicalDamageDealt": 35727,
            "totalChampionKills": 4,
            "totalAssists": 35,
            "mostChampionKillsPerSession": 3,
            "totalDamageDealt": 190815,
            "totalFirstBlood": 0,
            "totalSessionsLost": 2,
            "totalSessionsWon": 2,
            "totalMagicDamageDealt": 145353,
            "totalGoldEarned": 30823,
            "totalPentaKills": 0,
            "totalTurretsKilled": 2,
            "mostSpellsCast": 0,
            "maxNumDeaths": 7,
            "totalUnrealKills": 0
         }
      },
      {
         "id": 43,
         "stats": {
            "totalDeathsPerSession": 103,
            "totalSessionsPlayed": 24,
            "totalDamageTaken": 335867,
            "totalQuadraKills": 0,
            "totalTripleKills": 0,
            "totalMinionKills": 828,
            "maxChampionsKilled": 10,
            "totalDoubleKills": 2,
            "totalPhysicalDamageDealt": 170141,
            "totalChampionKills": 77,
            "totalAssists": 302,
            "mostChampionKillsPerSession": 10,
            "totalDamageDealt": 923985,
            "totalFirstBlood": 0,
            "totalSessionsLost": 7,
            "totalSessionsWon": 17,
            "totalMagicDamageDealt": 732367,
            "totalGoldEarned": 242157,
            "totalPentaKills": 0,
            "totalTurretsKilled": 12,
            "mostSpellsCast": 0,
            "maxNumDeaths": 8,
            "totalUnrealKills": 0
         }
      },
      {
         "id": 117,
         "stats": {
            "totalDeathsPerSession": 150,
            "totalSessionsPlayed": 36,
            "totalDamageTaken": 494142,
            "totalQuadraKills": 0,
            "totalTripleKills": 0,
            "totalMinionKills": 2017,
            "maxChampionsKilled": 8,
            "totalDoubleKills": 5,
            "totalPhysicalDamageDealt": 297987,
            "totalChampionKills": 102,
            "totalAssists": 418,
            "mostChampionKillsPerSession": 8,
            "totalDamageDealt": 1905782,
            "totalFirstBlood": 0,
            "totalSessionsLost": 13,
            "totalSessionsWon": 23,
            "totalMagicDamageDealt": 1577943,
            "totalGoldEarned": 353798,
            "totalPentaKills": 0,
            "totalTurretsKilled": 15,
            "mostSpellsCast": 0,
            "maxNumDeaths": 12,
            "totalUnrealKills": 0
         }
      },
      {
         "id": 254,
         "stats": {
            "totalDeathsPerSession": 13,
            "totalSessionsPlayed": 2,
            "totalDamageTaken": 43839,
            "totalQuadraKills": 0,
            "totalTripleKills": 0,
            "totalMinionKills": 77,
            "maxChampionsKilled": 8,
            "totalDoubleKills": 0,
            "totalPhysicalDamageDealt": 227018,
            "totalChampionKills": 12,
            "totalAssists": 8,
            "mostChampionKillsPerSession": 8,
            "totalDamageDealt": 247686,
            "totalFirstBlood": 0,
            "totalSessionsLost": 1,
            "totalSessionsWon": 1,
            "totalMagicDamageDealt": 3920,
            "totalGoldEarned": 21321,
            "totalPentaKills": 0,
            "totalTurretsKilled": 0,
            "mostSpellsCast": 0,
            "maxNumDeaths": 9,
            "totalUnrealKills": 0
         }
      }
   ],
   "summonerId": 21193669
}

我想得到3个champions中拥有最多totalSessionsPlayed的id。为此，我首先将champions按totalSessionsPlayed排序，然后取前3个id。我怎样才能做到这一点，或者有没有更好的方法来代替先分类呢

Answer 1

如果我正确理解这个问题，您可以使用heapq.nlargest到partially sort您的数组：

import json
import heapq

dat = json.loads("(your json here)")
champions = dat['champions']
tsp_getter = lambda x: x['stats']['totalSessionsPlayed']
largest = heapq.nlargest(3, champions, key = tsp_getter)
ids = [c['id'] for c in largest]

但是，简单的sorted可能会比nlargest更好地发挥作用（您可以做基准测试来检查它）：

tsp_getter = lambda x: - x['stats']['totalSessionsPlayed']
largest = sorted(champions, key = tsp_getter)
ids = [c['id'] for c in largest[:3]]