OpenEuphoria

Re: Sorting by sequence member`

• Posted by "Juergen Luethje" <j.lue at gmx.de> Oct 10, 2004
• 413 views

Tony Steward wrote:

> I have looked at custom sort and the demo csort.exe but it just
> doesn't sink in how to do it.
>
> Can't run csort.ex as xp complains about running dos program
>
> Tony
>
>
> On Sun, 10 Oct 2004 02:10:07 -0700, irv mullins <guest at rapideuphoria.com>
> wrote:
>>
>> posted by: irv mullins <irvm at ellijay.com>
>>
>> Tony Steward wrote:
>>>
>>> Kat your sorttok doesn't seem to like my data layout (i think) as it
>>> returns nothing.
>>
>>
>> Tony: I think custom_sort() will do what you want. Look it up in the
>> docs (it's 5 a.m. here, I've been up since 2 a.m. and am too groggy to
>> write a demo :)

The following code is slightly modified after the code that Andy Serpa
posted here on 25 Feb 2003. Very clean, straightforward, and flexible.
Thanks again, Andy!

object sort_i

function compare_index (object x1, object x2)
   -- Don't call this function directly, see below.
   integer comp, ix

   if integer(sort_i) then
      if sort_i > 0 then
         return  compare(x1[sort_i], x2[sort_i])
      else
         return -compare(x1[-sort_i], x2[-sort_i])
      end if
   end if

   for j = 1 to length(sort_i) do
      ix = sort_i[j]
      if ix > 0 then
         comp =  compare(x1[ix], x2[ix])
      else
         comp = -compare(x1[-ix], x2[-ix])
      end if
      if comp != 0 or j = length(sort_i) then
         return comp
      end if
   end for
end function

global function flex_sort (sequence s, object i)
   -- This is the function you actually call.
   -- s = sequence to be sorted (assumed to be at least 2-dimensional)
   -- i = integer index of element (column) to sort on,
   -- or sequence of indexes to sort on multiple fields
   -- (in order of preference).
-- If any given index is positive, then it will sort that element in
   ascending order.
   -- If negative, it will sort that element in descending order.
   sort_i = i
   return custom_sort(routine_id("compare_index"), s)
end function

Regards,
   Juergen

-- 
.... there are two ways of constructing a software design: One way is to
make it so simple that there are /obviously/ no deficiencies and the other
is to make it so complicated that there are no /obvious/ deficiencies.
[C.A.R. Hoare (1987), The Emperor's Old Clothes]