Re: %lookup

[Hans Boldt <boldt@xxxxxxxxxx>]

Jon Paris wrote:
>  >> If this is true, SORTA doesn't really help speed up the search.  Is that
> correct?
>
> No.  But it depends on the specification of the array.  If the array has the
> keyword ascend or descend on the definition, then %lookup will do a binary
> search which is orders of magnitude faster.  It is this keyword that
> triggers the binary search - not the SORTA.
>
> Ensure that your arrays are in sequence (sorting with sorta, qsort or
> whatever) and you will find your lookups work at light speed!

Wellll, it still depends on a lot of varying factors. For example, if 
you're only doing one or two lookups on a particular set of data, then 
sorting the data will only slow you down, and you may well be better off 
with a sequential search.

Any time you're dealing with performance you have to remember one 
important thing: When coding for performance, it is vital to test using 
proper performance measuring methods. I've personally seen situations 
where changes made with the aim of improving performance actually made 
matters worse! Tools are important in determining if a performance 
improvement in one area of code has negative impacts elsewhere. And on 
the subject of sorting and searching, the expected distribution of data 
also has an influence on choice of algorithm. Even the lowly Bubble Sort 
works very fast when the data is already mostly sorted.

Cheers! Hans