Maximum of two tuples

Question

The Python documentation states that, when called with more than one argument, max() returns the largest of the arguments.

>>> a = (1, 1, 1, 9)
>>> b = (4, 5, 6)
>>> max(a, b)
(4, 5, 6)

What defines how large a tuple, in this context, is? The tuple a has both a higher number of elements (four versus three) and its maximum value (9) is greater than the maximum number that can be found in b (6), so by any criteria I would have expected it to be the returned one. How are the tuples being compared by max()?

Answer 1

Tuples like all other sequences are ordered lexicographically: the order of two tuples is decided by the first position where the tuples differ. Quoting from python reference:

Tuples and lists are compared lexicographically using comparison of corresponding elements.

Your two tuples differ on the first position and since 4 > 1, we have

>>> (4, 5, 6) > (1, 1, 1, 9)
True

Answer 2

From left to right it compares each element of the tuples until it finds one larger than the other. This tuple is then returned. For example

>>> a = (2,0,0,0)
>>> b= (1,1,1,1)
>>> max(a,b)
(2, 0, 0, 0)

>>> b = (2,1,1,1)
>>> max(a,b)
(2, 1, 1, 1)

After an element is found in one tuple that is larger than the respective element in the other the remaining values have no effect on which tuple is returned.