There is a list of tuple like
有一个元组列表
l = [(1, 2, 'a', 'b'), (3, 4, 'c', 'd'), (5, 6, 'e', 'f')]
I can use
我可以用
[(i[0], i[2], i[3]) for i in l]
to get the result
得到结果
[(1, 'a', 'b'), (3, 'c', 'd'), (5, 'e', 'f')]
But if given a variable list such as [0, 2, 3], how to get the similar result?
但如果给出一个变量列表，如[0,2,3]，如何得到类似的结果？
2 个解决方案
#1
8
Use operator.itemgetter, like this
像这样使用operator.itemgetter
>>> from operator import itemgetter
>>> getter = itemgetter(0, 2, 3)
>>> [getter(item) for item in l]
[(1, 'a', 'b'), (3, 'c', 'd'), (5, 'e', 'f')]
If you have a list of indices, then you can unpack them to the itemgetter, like this
如果你有一个索引列表，那么你可以将它们解压缩到itemgetter，就像这样
>>> getter = itemgetter(*[0, 2, 3])
>>> [getter(item) for item in l]
[(1, 'a', 'b'), (3, 'c', 'd'), (5, 'e', 'f')]
#2
5
You could use a generator expression and tuple() to pull out specific indices:
您可以使用生成器表达式和tuple（）来提取特定索引：
[tuple(t[i] for i in indices) for t in l]
or you can use a operator.itemgetter() object to create a callable that does the same:
或者您可以使用operator.itemgetter（）对象来创建执行相同操作的可调用对象：
from operator import itemgetter
getindices = itemgetter(*indices)
[getindices(t) for t in l]
where indices is your list of indexes. This works because operator.itemgetter() just happens to return a tuple object when retrieving multiple indexes.
其中indices是您的索引列表。这是有效的，因为operator.itemgetter（）恰好在检索多个索引时返回一个元组对象。
Demo:
演示：
>>> l = [(1, 2, 'a', 'b'), (3, 4, 'c','d'), (5, 6, 'e','f')]
>>> indices = [0, 1, 2]
>>> [tuple(t[i] for i in indices) for t in l]
[(1, 2, 'a'), (3, 4, 'c'), (5, 6, 'e')]
>>> getindices = itemgetter(*indices)
>>> from operator import itemgetter
>>> [getindices(t) for t in l]
[(1, 2, 'a'), (3, 4, 'c'), (5, 6, 'e')]
#1
8
Use operator.itemgetter, like this
像这样使用operator.itemgetter
>>> from operator import itemgetter
>>> getter = itemgetter(0, 2, 3)
>>> [getter(item) for item in l]
[(1, 'a', 'b'), (3, 'c', 'd'), (5, 'e', 'f')]
If you have a list of indices, then you can unpack them to the itemgetter, like this
如果你有一个索引列表，那么你可以将它们解压缩到itemgetter，就像这样
>>> getter = itemgetter(*[0, 2, 3])
>>> [getter(item) for item in l]
[(1, 'a', 'b'), (3, 'c', 'd'), (5, 'e', 'f')]
#2
5
You could use a generator expression and tuple() to pull out specific indices:
您可以使用生成器表达式和tuple（）来提取特定索引：
[tuple(t[i] for i in indices) for t in l]
or you can use a operator.itemgetter() object to create a callable that does the same:
或者您可以使用operator.itemgetter（）对象来创建执行相同操作的可调用对象：
from operator import itemgetter
getindices = itemgetter(*indices)
[getindices(t) for t in l]
where indices is your list of indexes. This works because operator.itemgetter() just happens to return a tuple object when retrieving multiple indexes.
其中indices是您的索引列表。这是有效的，因为operator.itemgetter（）恰好在检索多个索引时返回一个元组对象。
Demo:
演示：
>>> l = [(1, 2, 'a', 'b'), (3, 4, 'c','d'), (5, 6, 'e','f')]
>>> indices = [0, 1, 2]
>>> [tuple(t[i] for i in indices) for t in l]
[(1, 2, 'a'), (3, 4, 'c'), (5, 6, 'e')]
>>> getindices = itemgetter(*indices)
>>> from operator import itemgetter
>>> [getindices(t) for t in l]
[(1, 2, 'a'), (3, 4, 'c'), (5, 6, 'e')]