如何合并两个列表

Question

我可以用两种方式编写追加行。两者都不会产生预期的结果。有没有办法将其包含在 1 行中？

选项 1：

row.append(x[1] for x in emails if x[0] == row[1])

产量：

[['project1', 'email1', <generator object <genexpr> at 0x0227D670>], ['project1', 'email2', <generator object <genexpr> at 0x022EB8A0>]]

选项 2：

row.append([x[1] for x in emails if x[0] == row[1]])

产量：

[['project1', 'email1', ['john@gmail.com']], ['project1', 'email2', ['bill@gmail.com']]]

期望的结果：

[['project1', 'email1', 'john@gmail.com'], ['project1', 'email2', 'bill@gmail.com']]

代码：

emails = [['email1','john@gmail.com'],['email2','bill@gmail.com']]

projects = [['project1', 'email1'], ['project1', 'email2']]

for row in projects:
    row.append(x[1] for x in emails if x[0] == row[1])
print projects

Answer 1

emails = [['email1','john@gmail.com'],['email2','bill@gmail.com']]

projects = [['project1', 'email1'], ['project1', 'email2']]
from itertools import chain


print([list(set((chain.from_iterable(ele)))) for ele in zip(emails,projects)])
[['email1', 'john@gmail.com', 'project1'], ['email2', 'project1', 'bill@gmail.com']]

或者：

print([list(set(ele).union(projects[ind])) for ind, ele in enumerate(emails)])

或者：

print([projects[ind] + [ele for ele in sub if ele not in projects[ind]] for ind, sub in enumerate(emails)])

所有不同的版本都适用于多个项目，而不仅仅是检查单个元素。

Answer 2

在您现有的代码中，替换这一行：

row.append(x[1] for x in emails if x[0] == row[1])

与：

row.extend(x[1] for x in emails if x[0] == row[1])

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或者，消除循环并将代码全部压缩到一行中：

>>> projects = [  row + [x[1] for x in emails if x[0] == row[1]] for row in projects ]
>>> print projects 
[['project1', 'email1', 'john@gmail.com'], ['project1', 'email2', 'bill@gmail.com']]

如何合并两个列表

How to combine two lists

python

list-comprehension

python-2.7

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