AppendTo VERY slow
- To: mathgroup at smc.vnet.net
- Subject: [mg35279] AppendTo VERY slow
- From: M.P.Croucher at Sheffield.ac.uk (Mike)
- Date: Sat, 6 Jul 2002 05:44:22 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
I use lists a lot in mathematica and tend to use AppendTo[] a lot in
my programs. Recently I wrote a function that i call over and over
again and found that the results were coming very slowly and i MEAN
slowly. I was doing Fourier Transforms and all kinds of stuff so I
put it down to those at first but I have just put in a load of Print
statements just after each part of the function to see what was taking
so long.
I was amazed to see that the Fourier Transforms were so quick and what
was actually taking the time was a part of my function that collected
the results togther in the form I wanted and outputted the result. It
looks like this
Do[
elem = {xlist[[count]], ylist[[count]]]};
AppendTo[outlist, elem];
, {count, 1, number}
];
It seems that as the list grows it gets slower and slower. Any tips
on a way around this would be greatly appreciated (would speed my life
up no end)
Thank
Mike
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