[英]Iterate a list with indexes in Python
I could swear I've seen the function (or method) that takes a list, like this [3, 7, 19]
and makes it into iterable list of tuples, like so: [(0,3), (1,7), (2,19)]
to use it instead of:我可以发誓我已经看到了 function (或方法),它需要一个列表,像这样
[3, 7, 19]
并使其成为可迭代的元组列表,如下所示: [(0,3), (1,7), (2,19)]
来代替:
for i in range(len(name_of_list)):
name_of_list[i] = something
but I can't remember the name and googling "iterate list" gets nothing.但我不记得名字和谷歌搜索“迭代列表”一无所获。
>>> a = [3,4,5,6]
>>> for i, val in enumerate(a):
... print i, val
...
0 3
1 4
2 5
3 6
>>>
Here's another using the zip
function.这是另一个使用
zip
函数的方法。
>>> a = [3, 7, 19]
>>> zip(range(len(a)), a)
[(0, 3), (1, 7), (2, 19)]
Here it is a solution using map function:这是使用 map 函数的解决方案:
>>> a = [3, 7, 19]
>>> map(lambda x: (x, a[x]), range(len(a)))
[(0, 3), (1, 7), (2, 19)]
And a solution using list comprehensions:以及使用列表推导式的解决方案:
>>> a = [3,7,19]
>>> [(x, a[x]) for x in range(len(a))]
[(0, 3), (1, 7), (2, 19)]
python enumerate
function will be satisfied your requirements python
enumerate
函数将满足您的要求
result = list(enumerate([1,3,7,12]))
print result
output输出
[(0, 1), (1, 3), (2, 7),(3,12)]
If you have multiple lists, you can do this combining enumerate
and zip
:如果您有多个列表,您可以结合
enumerate
和zip
执行此操作:
list1 = [1, 2, 3, 4, 5]
list2 = [10, 20, 30, 40, 50]
list3 = [100, 200, 300, 400, 500]
for i, (l1, l2, l3) in enumerate(zip(list1, list2, list3)):
print(i, l1, l2, l3)
Output:
0 1 10 100 1 2 20 200 2 3 30 300 3 4 40 400 4 5 50 500
Note that parenthesis is required after i
.请注意,
i
之后需要括号。 Otherwise you get the error: ValueError: need more than 2 values to unpack
否则你会得到错误:
ValueError: need more than 2 values to unpack
something = list(enumerate([1,3,7,12])) print something something = list(enumerate([1,3,7,12]))打印内容
output [(0, 1), (1, 3), (2, 7),(3,12)]
输出[(0,1),(1,3),(2,7),(3,12)]
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