Python: Minimum of lists using custom function

Question

If I create a list of tuples lst = [(0,5), (5,0), (2,2)] and use min(lst), it returns (0,5).

How does python decide which tuple to be the smallest?

Is it using first element of tuple to make a decision?

How should I change it to return minimum sum of tuple assuming there are only 2 elements in tuples?

Possible duplicate of How does the min/max function on a nested list work? — baduker
– baduker, Commented Mar 11, 2018 at 0:39
@YoungBinJo, if one of the below solutions helped, consider accepting it (green tick on left) so other users know. — jpp
– jpp, Commented Mar 22, 2018 at 13:19

jpp · Accepted Answer · 2018-03-11 01:19:22Z

2

You can use a custom key with min.

lst = [(0,5), (5,0), (2,2)]

res = min(lst, key=lambda x: sum(x))
# (2, 2)

If you wish to retrieve element with minimum sum sorted by first element, you can specify a tuple key:

lst2 = [(0,5), (5,0), (2,2), (1,3)]

res = min(lst2, key=lambda x: (sum(x), x[0]))
# (1, 3)

Without using the tuple key, the result above would be (2,2).

answered Mar 11, 2018 at 0:34

jpp

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1 Comment

also, first and third element have different sums (5 versus 4).