如何在python中合并二维列表的内部列表

Question

我有一个像这样的二维列表：[['dragon', 11], ['dragon', 111], ['stage_1', 1], ['stage_1', 2], ['stage_2', 10], ['stage_2', 12]].我希望它看起来像这样：[['dragon', [11, 111]], ['stage_1', [1, 2]], ['stage_2', [10, 12]]]

Answer 1

对于您的 2d 列表结构，您可以使用 zip 和列表理解

lst = [['dragon', 11], ['dragon', 111], ['stage_1', 1], ['stage_1', 2], ['stage_2', 10], ['stage_2', 12]]

k, v = zip(*lst)

result = [[k[i], v[i:i+2]]  for i in range(0, len(k), 2)]

print(result)

输出

[['dragon', (11, 111)], ['stage_1', (1, 2)], ['stage_2', (10, 12)]]

性能比较

1.列表理解/压缩

    k, v = zip(*lst)

    result = [[k[i], v[i:i+2]]  for i in range(0, len(k), 2)]

    100000 loops, best of 3: 3.72 µs per loop (using timeit)

2.字典

d = defaultdict(list)

for k, v in lst:

    d[k].append(v)

groups = list(map(list, d.items()))

100000 loops, best of 3: 5.85 µs per loop (using timeit)

结果：列表理解速度快约 57%

Answer 2

有collections.defaultdict对象：

from collections import defaultdict

lst = [['dragon', 11], ['dragon', 111], ['stage_1', 1], ['stage_1', 2], ['stage_2', 10], ['stage_2', 12]]

d = defaultdict(list)

for k, v in lst:

    d[k].append(v)

groups = list(map(list, d.items()))

print(groups)

输出：

[['dragon', [11, 111]], ['stage_1', [1, 2]], ['stage_2', [10, 12]]]

Answer 3

我认为最好为您的情况使用字典，如下所示

d = { }

for key,value in ls:

    d[key] = d.get(key, []) + [value]

print(d)

d.items()如果需要列表，可以使用获取元组列表