在Python中的元组列表中查找最大值[duplicate]

Possible Duplicate:
Sorting or Finding Max Value by the second element in a nested list. Python

可能的重复:通过嵌套列表中的第二个元素排序或查找最大值。Python

I have a list with ~10^6 tuples in it like this:

我有一个列表,这样~ 10 ^ 6元组:

[(101, 153), (255, 827), (361, 961), ...]
  ^     ^
  X     Y

I want to find the maximum value of the Ys in this list, but also want to know the X that it is bound to.

我想在这个列表中找到y的最大值，但同时也想知道它所绑定的X。

How do I do this?

我该怎么做呢?

3 个解决方案

#1

Use max():

使用max():

Using itemgetter():

使用itemgetter():

In [53]: lis=[(101, 153), (255, 827), (361, 961)]

In [81]: from operator import itemgetter

In [82]: max(lis,key=itemgetter(1))[0]    #faster solution
Out[82]: 361

using lambda:

使用λ:

In [54]: max(lis,key=lambda item:item[1])
Out[54]: (361, 961)

In [55]: max(lis,key=lambda item:item[1])[0]
Out[55]: 361

timeit comparison:

时间比较:

In [30]: %timeit max(lis,key=itemgetter(1))
1000 loops, best of 3: 232 us per loop

In [31]: %timeit max(lis,key=lambda item:item[1])
1000 loops, best of 3: 556 us per loop

#2

In addition to max, you can also sort:

除了max，你还可以排序:

>>> lis
[(101, 153), (255, 827), (361, 961)]
>>> sorted(lis,key=lambda x: x[1], reverse=True)[0]
(361, 961)

#3

You could loop through the list and keep the tuple in a variable and then you can see both values from the same variable...

您可以循环遍历列表并将tuple保存在一个变量中，然后您可以从同一个变量中看到两个值……

num=(0, 0)
for item in tuplelist:
  if item[1]>num[1]:
    num=item #num has the whole tuple with the highest y value and its x value

#1