Making Revolution faster with really big arrays

[Dick Kriesel]

On 4/12/05 7:36 PM, "Dennis Brown" <see3d at writeme.com> wrote:

> ...I have two arrays 10,000 lines with 2500 items in each line...
> ...I need to pair the items together...

Do you have something like closing prices in one container and shares traded
in another container, each for the same 10,000 securities over the same
2,500 trading days?  If so, do you want to calculate something like trading
volume as price * shares?

If so, then here's a way to bring together the values from one such list
with the values from another, without waiting for any chunk expressions.  On
my machine, generating a 10,000 line by 2,500 item list of integers to
prepare for the test took about three minutes.  Then bringing together all
the pairs of lines from two lists, as you indicated in your initial email,
took about 1.2 seconds.

So you could do many passes through your big lists before the day is done,
and not need to wait for an extension to the language.
 
To try it, paste the following into the script of a new stack.  If I've
misunderstood or done something wrong, please let me know.

-- Dick
---------------------
global gList

on mouseUp
  if gList is empty then initialize
  combinePairsOfLines gList,gList
end mouseUp

on initialize
  put 10000 into tLineCount
  put 2500 into tItemCount
  put tLineCount && tItemCount & cr
  put the seconds into tSeconds
  repeat with i = 1 to tLineCount
    repeat with j = 1 to tItemCount
      put i + j & comma after tList
    end repeat
    put return after tList
    if i mod 1000 = 0 then put "line count so far:" && i & cr after msg
  end repeat
  put tList into gList -- save for reuse across edit-test cycles
  put "elapsed seconds to initialize:" && \
      the seconds - tSeconds & cr after msg
end initialize

on combinePairsOfLines pList1,pList2
  put the long seconds into tSeconds
  split pList2 using return
  put 0 into i
  repeat for each line tLineFromList1 in pList1
    add 1 to i
    put tLineFromList1 & pList2[i] into tCombinedLine
    -- doSomethingWithCombinedLine tCombinedLine
  end repeat
  put "elapsed seconds to combine pairs:" && \
      the long seconds - tSeconds & cr after msg
end combinePairsOfLines