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pythonlisttuples

How to find the maximum value in a list of tuples?

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

[(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.

How do I do this?

Solution

  • operator.itemgetter():

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

In [81]: from operator import itemgetter

In [82]: max(lis, key=itemgetter(1))  # Faster solution
Out[82]: (361, 961)

In [83]: max(lis, key=itemgetter(1))[0]  # Faster solution
Out[83]: 361

    lambda:

    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 of operator.itemgetter vs lambda:

    In [84]: %timeit max(lis, key=itemgetter(1))
1000 loops, best of 3: 232 us per loop

In [85]: %timeit max(lis, key=lambda item: item[1])
1000 loops, best of 3: 556 us per loop