How to use Python left outer join using FOR/LIST/DICTIONARY comprehensions (not SQL)?

问题

I have two tuples, details below:

t1 = [
['aa'],
['ff'],
['er']
]

t2 = [
['aa', 11,],
['er', 99,]
]

and I would like to get results like these below using python method similar to SQL's LEFT OUTER JOIN:

res = [
['aa', 11,],
['ff',  0,],
['er', 99,]
]

Please help me with this.

回答1:

d2 = dict(t2)
res = [[k[0], d2.get(k[0], 0)] for k in t1]

来源：https://stackoverflow.com/questions/15099022/how-to-use-python-left-outer-join-using-for-list-dictionary-comprehensions-not