[PD] long list-building time

[Miller Puckette]

Hi all -

I don't think there's any way to implement [list append] that doesn't
require copying the list (tcl can do the append in place so doesn't have to
do that).  So building a list of length n requires a compute time on the
order of n^2 - which gets to be problematic when n gets big.

Another alternative to arrays might be textfiles - however, there aren't
yet very good  methods for getting the data back out of them :)

Miller

On Wed, Mar 13, 2013 at 09:12:51AM -0700, Jonathan Wilkes wrote:
> Hi list,
>      See attached for difference between building a list
> of symbols through [list append] and building an array
> of symbols.
> 
> 
> Now, I know the ds array resizing and setting is
> more efficient than building out a list using [list append],
> but I don't understand why the [list append] takes over
> a minute to complete.  It can't be due to symbol table
> stuff since I'm using the same symbol over and over.
> 
> I know tcl lappend works fairly fast.  Is there a way to
> speed up [list] stuff in Pd?
> 
> -Jonathan

> #N struct wa array a word;
> #N struct word symbol s;
> #N canvas 588 135 450 506 10;
> #N canvas 0 0 450 300 word 0;
> #X obj 108 40 struct word symbol s;
> #X restore 332 25 pd word;
> #N canvas 0 0 450 300 wa 0;
> #X obj 40 40 struct wa array a word;
> #X restore 330 71 pd wa;
> #X scalar wa \; foo \; \;;
> #X obj 174 217 pointer;
> #X obj 134 300 setsize wa a;
> #X obj 89 335 element wa a;
> #X msg 62 305 symbol foo;
> #X obj 62 201 until;
> #X obj 62 161 t a b;
> #X msg 111 184 0;
> #X obj 62 235 f;
> #X obj 107 235 + 1;
> #X obj 107 257 t a a;
> #X obj 62 273 t b a;
> #X obj 62 366 set -symbol word s;
> #X obj 192 15 bng 33 250 50 0 empty empty do_it. 41 16 0 10 -262144
> -1 -1;
> #X msg 174 140 traverse pd-dsresizing.pd \, next;
> #X obj 311 312 until;
> #X obj 311 282 t a b;
> #X msg 371 313 bang;
> #X obj 311 334 list append;
> #X obj 311 356 list append foo;
> #X msg 311 260 45000;
> #X obj 247 261 realtime;
> #X obj 292 165 bng 33 250 50 0 empty empty do_it. 41 16 0 10 -262144
> -1 -1;
> #X obj 292 203 t b b b;
> #X floatatom 247 283 8 0 0 0 - - -;
> #X obj 231 88 realtime;
> #X floatatom 231 110 8 0 0 0 - - -;
> #X obj 192 53 t b b b b;
> #X msg 62 139 45000;
> #X connect 3 0 4 1;
> #X connect 3 0 5 1;
> #X connect 5 0 14 1;
> #X connect 6 0 14 0;
> #X connect 7 0 10 0;
> #X connect 8 0 7 0;
> #X connect 8 1 9 0;
> #X connect 9 0 10 1;
> #X connect 10 0 11 0;
> #X connect 10 0 13 0;
> #X connect 11 0 12 0;
> #X connect 12 0 10 1;
> #X connect 12 1 4 0;
> #X connect 13 0 6 0;
> #X connect 13 1 5 0;
> #X connect 15 0 29 0;
> #X connect 16 0 3 0;
> #X connect 17 0 20 0;
> #X connect 18 0 17 0;
> #X connect 18 1 19 0;
> #X connect 19 0 20 1;
> #X connect 20 0 21 0;
> #X connect 21 0 20 1;
> #X connect 22 0 18 0;
> #X connect 23 0 26 0;
> #X connect 24 0 25 0;
> #X connect 25 0 23 1;
> #X connect 25 1 22 0;
> #X connect 25 2 23 0;
> #X connect 27 0 28 0;
> #X connect 29 0 27 1;
> #X connect 29 1 30 0;
> #X connect 29 2 16 0;
> #X connect 29 3 27 0;
> #X connect 30 0 8 0;

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