Python 迭代元组列表
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Iterate a list of tuples
提问by Clev3r
I'm looking for a clean way to iterate over a list of tuples where each is a pair like so [(a, b), (c,d) ...]. On top of that I would like to alter the tuples in the list.
我正在寻找一种干净的方法来迭代一个元组列表，其中每个元组都是这样的一对[(a, b), (c,d) ...]。最重要的是，我想更改列表中的元组。
Standard practice is to avoid changing a list while also iterating through it, so what should I do? Here's what I kind of want:
标准做法是在迭代列表的同时避免更改列表，那么我该怎么办？这是我想要的：
for i in range(len(tuple_list)):
a, b = tuple_list[i]
# update b's data
# update tuple_list[i] to be (a, newB)
采纳答案by Martijn Pieters
Just replace the tuples in the list; you canalter a list while looping over it, as long as you avoid adding or removing elements:
只需替换列表中的元组；您可以在循环时更改列表，只要您避免添加或删除元素：
for i, (a, b) in enumerate(tuple_list):
new_b = some_process(b)
tuple_list[i] = (a, new_b)
or, if you can summarize the changes to binto a function as I did above, use a list comprehension:
或者，如果您可以b像我上面所做的那样将更改总结为一个函数，请使用列表理解：
tuple_list = [(a, some_process(b)) for (a, b) in tuple_list]
回答by Udo Klein
Why don't you go for a list comprehension instead of altering it?
你为什么不去进行列表理解而不是改变它？
new_list = [(a,new_b) for a,b in tuple_list]
回答by Jonathan Vanasco
here are some ideas:
这里有一些想法：
def f1(element):
return element
def f2(a_tuple):
return tuple(a_tuple[0],a_tuple[1])
newlist= []
for i in existing_list_of_tuples :
newlist.append( tuple( f1(i[0]) , f(i1[1]))
newlist = [ f2(i) for i in existing_list_of_tuples ]
