[Tutor] operations on lists

[Alan Gauld]

On 13/04/16 20:41, marcus lütolf wrote:
> Hello experts
> 
> I'am working exercise 5. of 'Practical Programming 2nd edition, .....using Python 3'  (operations on lists).
> The following code get's me wrong results:
> 
>>>> metals = [['beryllium', 4],['magnesium', 12], ['calcium', 20], ['strontium', 38], ['barium', 56], ['radium', 88]]
>>>> max(metals)
> ['strontium', 38]
>>>> min(metals)
> ['barium', 56]
> 
> It should return 
> ['radium', 88] and 
> ['beryllium', 4] respectively

Why should it return radium as the max?

It may be obvious to you but looking at it as simple data
(which is all Python sees) that's not obvious at all.
Why would radium come before strontium? And obviously(!)
the first list element takes priority over the second
when looking at simple data. (And Python just sees a
collection of string/integer pairs, it has no idea what
those strings/integers mean)

If you want to order by the second element there are several
things you can do, the simplest is probably to just swap
the elements around in your tuples... But that might not
be possible (or easy) depending on how you get the tuples.


-- 
Alan G
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