python - 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一行中？

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

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])

在线解决方案

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']]