2011/1/5 Florian Pflug <f...@phlo.org>: > On Jan5, 2011, at 15:17 , Pavel Stehule wrote: >> 2011/1/5 Florian Pflug <f...@phlo.org>: >>> How so? You'd still be able to get the last element by simply writing >>> >>> array_relative(some_array, array[-1]). >>> >>> Or, if we made the function variadic, by writing >>> >>> array_relative(some_array, -1). >> >> Sorry, but It isn't too intuitive. Minimally for me. Why you don't >> thinking about simple functions with only positive arguments. There >> are only four combinations. I don't think we must have only one super >> function. >> >> we need functionality for: >> >> a) get first n items >> b) get items without last n items >> c) get last n items >> d) skip first n items > > Now you've moved the goalpost - the OP wanted to access individual > elements, not slices! To support slices, a three-argument version > of array_relative() would be required, with the signature >
I am not sure. Usually need both when I play with a stack I need a) FIFO - first element from array and all others without first element b) LIFO - last element from array and all others without last element The game with queues is only one use case that I know where I need access to relative indexed items in array. Maybe is other, but I don't know it. ??? I don't know why I need a access to relative indexed items? Pavel > array_relative(some_array anyarray, first int[], last int[]) > > Your requirements (a) to (d) are then easily satisfied > > a) array_relative(ary, array[0], array[n-1]) > b) array_relative(ary, array[0], array[-n-1]) > c) array_relative(ary, array[-n], array[-1]) > d) array_relative(ary, array[n], array[-1]) > what is n?? it's not implementable. > The individual function approach might be a tad more readable for > one-dimensional arrays, but they don't scale well to the general > case. > > Maybe the OP could comment on whether any of these solutions > would fit his needs? > > best regards, > Florian Pflug > > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
