Question

我想将值附加到现有字典中。这是我的代码：

tmp_result = [{'M': 8}, {'N': 16},]
cross_configs = [({'device': 'cpu'},), ({'device': 'cuda'},)]

import copy
generated_configs = []
for config in cross_configs:
    for value in config:
            new_value = copy.deepcopy(tmp_result)
            new_value.append(value)
            generated_configs.append(new_value)

print (generated_configs)

Output: 
[[{'M': 8}, {'N': 16}, {'device': 'cpu'}], [{'M': 8}, {'N': 16}, {'device': 'cuda'}]]

我不喜欢进行深度复制和附加的内部循环。什么是Python的方式做到这一点？

Answer 1

您可以进行列表理解：

[tmp_result + list(x) for x in cross_configs]

示例：

tmp_result = [{'M': 8}, {'N': 16},]
cross_configs = [({'device': 'cpu'},), ({'device': 'cuda'},)]

print([tmp_result + list(x) for x in cross_configs])
# [[{'M': 8}, {'N': 16}, {'device': 'cpu'}], [{'M': 8}, {'N': 16}, {'device': 'cuda'}]]

Answer 2

嵌套列表理解就足够了；在给出的示例中，对dict的显式调用足以避免需要deepcopy。

generated_configs = [[dict(y) for y in tmp_result + list(x)] for x in cross_configs]

如果您反对tmp_result + list(x)，请改用itertools.chain。

from itertools import chain
generated_configs = [[dict(y) for y in chain(tmp_result, x)] for x in cross_configs]

合并两个列表的Python方式

2 个答案: