如何合并具有相同元素的不同列表

Question

查询数据库返回的结果

["www.google.com","2019-1-2","102"],
["www.fb.com","2019-1-4","292"],
["www.amazon.com","2019-3-2","142"],
["www.google.com","2019-6-2","162"],
["www.fb.com","2019-8-2","52"],
["www.fb.com","2019-3-2","522"],
["www.google.com","2019-8-5","591"]

我想要的列表样式结果：

["www.google.com",["2019-1-2","102"],["2019-6-2","162"],["2019-8-5","591"]],
["www.fb.com",["2019-1-4","292"],["2019-8-2","52"],["2019-3-2","522"]],
["www.amazon.com",["2019-3-2","142"]]

或者一种字典风格。

{"www.google.com":[["2019-1-2","102"],["2019-6-2","162"],["2019-8-5","591"]]},
{"www.fb.com":[["2019-1-4","292"],["2019-8-2","52"],["2019-3-2","522"]]},
["www.amazon.com":["2019-3-2","142"]}

尝试比较列表的第一个元素

temp = arr[0]
for x in result:
    if x[0] == temp

Answer 1

您可以使用defaultdict和一些列表拼接来解决此问题

from collections import defaultdict

data = defaultdict(list)

db = [["www.google.com","2019-1-2","102"],
      ["www.fb.com","2019-1-4","292"],
      ["www.amazon.com","2019-3-2","142"],
      ["www.google.com","2019-6-2","162"],
      ["www.fb.com","2019-8-2","52"],
      ["www.fb.com","2019-3-2","522"],
      ["www.google.com","2019-8-5","591"]]

for d in db:
    data[d[0]].append(d[1:])

print(data)

将打印

defaultdict(list,
        {'www.amazon.com': [['2019-3-2', '142']],
         'www.fb.com': [['2019-1-4', '292'],
          ['2019-8-2', '52'],
          ['2019-3-2', '522']],
         'www.google.com': [['2019-1-2', '102'],
          ['2019-6-2', '162'],
          ['2019-8-5', '591']]})

Answer 2

使用dict.setdefault

d = {}
for x, y, z in l:
    d.setdefault(x, []).append([y, z])
print(d)

或者使用单行字典理解：

print({x: [[j, k] for i, j, k in l if i == x] for x, y, z in l})