Re: array_reverse()

On Mon, Nov 2, 2009 at 9:51 AM, Sam Mason <sam(at)samason(dot)me(dot)uk> wrote:
> On Mon, Nov 02, 2009 at 09:20:38AM -0500, Tom Lane wrote:
>> Craig Ringer <craig(at)postnewspapers(dot)com(dot)au> writes:
>> > Before I go ahead and try to write a decent quality version: is there
>> > any chance an array_reverse() function (in C) would be accepted into Pg
>> > mainline?
>>
>> What would it mean for a multi-dimensional array?
>
> Rotating the array by 180 degrees in every dimension would give the same
> answer for 1-dimensional arrays and give sensible answers for higher
> dimensional arrays.  For example:
>
>  1,2,3   ==  3,2,1
>
>  [1 2 3     [9 8 7
>   4 5 6  ==  6 5 4
>   7 8 9]     3 2 1]
>
> I think higher dimensionality would work, it's just a bit fiddly to
> draw.

do you think that's the typical case, or is it more common to want to
reverse a particular slice? (I like your idea actually, because if
you need a slice you can slice notation one out...better than what I
posted above).

merlin