How to find the maximum value in a list of tuples?
PythonListTuplesPython Problem Overview
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?
Python Solutions
Solution 1 - Python
Use max():
Using 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:
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:
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
Solution 2 - Python
In addition to max, you can also sort:
>>> lis
[(101, 153), (255, 827), (361, 961)]
>>> sorted(lis,key=lambda x: x[1], reverse=True)[0]
(361, 961)
Solution 3 - Python
You could loop through the list and keep the tuple in a variable and then you can see both values from the same variable...
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