Python：用另一个列表过滤列表列表
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Python: filter list of list with another list
提问by fj123x
i'm trying to filter a list, i want to extract from a list A (is a list of lists), the elements what matches they key index 0, with another list B what has a serie of values
我正在尝试过滤一个列表，我想从列表 A（是一个列表列表）中提取与它们匹配的元素键索引 0，另一个列表 B 具有一系列值
like this
像这样
list_a = list(
list(1, ...),
list(5, ...),
list(8, ...),
list(14, ...)
)
list_b = list(5, 8)
return filter(lambda list_a: list_a[0] in list_b, list_a)
should return:
应该返回：
list(
list(5, ...),
list(8, ...)
)
How can i do this? Thanks!
我怎样才能做到这一点？谢谢！
回答by Ashwini Chaudhary
Use a list comprehension:
使用列表理解：
result = [x for x in list_a if x[0] in list_b]
For improved performance convert list_bto a set first.
为了提高性能list_b，请先转换为一组。
As @kevin noted in comments something like list(5,8)(unless it's not a pseudo-code) is invalid and you'll get an error.
正如@kevin 在评论中指出的那样list(5,8)（除非它不是伪代码）是无效的，你会得到一个错误。
list()accepts only one item and that item should be iterable/iterator
list()只接受一项并且该项目应该是可迭代的/迭代器
回答by Ashwini Chaudhary
You are actually very close. Just do this:
你实际上非常接近。只需这样做：
list_a = list(
list(1, ...),
list(5, ...),
list(8, ...),
list(14, ...)
)
# Fix the syntax here
list_b = [5, 8]
return filter(lambda list_a: list_a[0] in list_b, list_a)
