[Python-Dev] Behaviour of max() and min() with equal keys

Matthew Woodcraft matthew at woodcraft.me.uk
Wed Sep 8 21:32:48 CEST 2010

Raymond Hettinger  <raymond.hettinger at gmail.com> wrote:

>Matthew Woodcraft wrote:
>> In CPython, the builtin max() and min() have the property that if there
>> are items with equal keys, the first item is returned. From a quick look
>> at their source, I think this is true for Jython and IronPython too.

>> However, this isn't currently a documented guarantee. Could it be made
>> so? (As with the decision to declare sort() stable, it seems likely that
>> by now there's code out there relying on it anyway.)

> That seems like a reasonable request.  This behavior has been around
> for a very long time is unlikely to change.  Elsewhere, we've made
> efforts to document sort stability (i.e. sorted(), heapq.nlargest(),
> heapq.nsmallest, merge(), etc).

I've submitted issue 9802 as a feature request with a concrete suggestion for
the docs.


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