[PD] array-abs

Matt Barber brbrofsvl at gmail.com
Sun Oct 4 21:43:49 CEST 2015

```It takes almost a full second to output a list of n=1,000,000 with a
100-cycle until on my computer.

On Sun, Oct 4, 2015 at 3:38 PM, Matt Barber <brbrofsvl at gmail.com> wrote:

> This is still much slower than [list-drip], and it freezes Pd for me when
> I get up to lists of n=100,000 or so. I think it's because Pd has to copy
> the list to an output every cycle of [until], so when n=10, you're only
> outputting something of size 10 10 times, but that grows by n^2 so when
> it's n=10,000 times 10,000 outputs, it's a lot. 1,000,000 seems impossible
> unless the list decreases in size each cycle, which it does in [list-drip],
> recursively.
>
> On Sun, Oct 4, 2015 at 2:48 PM, Miller Puckette <msp at ucsd.edu> wrote:
>
>> Here's a way to serialize a list in (I believe) linear time:
>>
>> #N canvas 881 291 450 300 10;
>> #X msg 136 14 list 3 . 1 4 1 5 9;
>> #X obj 83 97 list length;
>> #X obj 77 211 list split;
>> #X obj 101 186 list;
>> #X obj 139 55 t l b l;
>> #X obj 83 119 until;
>> #X obj 83 141 f;
>> #X obj 114 142 + 1;
>> #X msg 166 117 0;
>> #X obj 83 163 t b f;
>> #X obj 117 278 print;
>> #X obj 116 250 list split 1;
>> #X connect 0 0 4 0;
>> #X connect 1 0 5 0;
>> #X connect 2 1 11 0;
>> #X connect 3 0 2 0;
>> #X connect 4 0 1 0;
>> #X connect 4 1 8 0;
>> #X connect 4 2 3 1;
>> #X connect 5 0 6 0;
>> #X connect 6 0 7 0;
>> #X connect 6 0 9 0;
>> #X connect 7 0 6 1;
>> #X connect 8 0 6 1;
>> #X connect 9 0 3 0;
>> #X connect 9 1 2 1;
>> #X connect 11 0 10 0;
>>
>> cheers
>> Miller
>>
>> On Sun, Oct 04, 2015 at 02:27:37PM -0400, Matt Barber wrote:
>> > Your [pd drip] does a lot of extra work. It's go basically linear stack
>> > performance, and you're recopying the list every loop (an until loop
>> would
>> > solve this for a little extra cpu time). The secret of [list-drip] is
>> that
>> > it doesn't recopy the list using the [list] object, and it avoids stack
>> > overflows by doing the recursion split at the midpoint of the list and
>> only
>> > outputting when it's done the binary split down to lists of size 1,
>> which
>> > are the elements, or size zero, which are bangs (and which are filtered
>> > out).
>> >
>> > Since it's binary recursion on the list, the stack only grows
>> > proportionally to log_2(n), which is about 20 for n=1,000,000. It's
>> still
>> > going to be slower than an object written in C that can just iterate
>> over
>> > the contents in a single loop, and lists in Pd are slower in general
>> than
>> > arrays, so an until loop and tabread over an array is going to be
>> quicker.
>> > It is much slower for copying though -- an until loop with tabread and
>> > tabwrite has way more overhead than an [array get]-[array set] pair.
>> >
>> >
>> > On Sun, Oct 4, 2015 at 1:06 PM, Christof Ressi <christof.ressi at gmx.at>
>> > wrote:
>> >
>> > > Please don't use the previous version of the multi-dimensional
>> arrays!!!
>> > > First, I forget to get rid of one [drip] object. Second, I discovered
>> that
>> > > [pd drip] will create a stack overflow if there are more than ca. 300
>> > > elements! (Why???) So I replaced it with [list-drip] which works fine.
>> > >
>> > > So here's the corrected pure vanilla version + a zexy version using
>> > > [drip]. I prefer to use the latter one because it's waaaaay faster
>> than all
>> > > the drip abstractions based on [list split].
>> > >
>> > > Vanilla:
>> https://www.dropbox.com/s/wd0avxtaneqgdic/carray_vanilla.zip?dl=0
>> > > Zexy: https://www.dropbox.com/s/ea8kihwbdqhcajr/carray_zexy.zip?dl=0
>> > >
>> > > Christof
>> > >
>> > > PS:  I did a benchmark test of iterating through an array of 1 million
>> > > elements, using [realtime], and here's what I found on my system:
>> > >
>> > > [array get] + [drip] --> ca. 6.5-9ms
>> > > [until] + [tabread] --> ca. 120-200ms
>> > > [array get] + [list-drip] --> ca. 340-400ms
>> > >
>> > > To me this result was a bit surprising...
>> > >
>> > > You can test yourself with the attached patch.
>> > > *Gesendet:* Sonntag, 04. Oktober 2015 um 17:32 Uhr
>> > > *Von:* "Christof Ressi" <christof.ressi at gmx.at>
>> > > *An:* "Matt Barber" <brbrofsvl at gmail.com>
>> > >
>> > > *Cc:* Pd-List <pd-list at lists.iem.at>
>> > > *Betreff:* Re: [PD] array-abs
>> > > Wow, looks cool!
>> > >
>> > > Just a few days ago I reworked some of my personal table abstractions,
>> > > which also make use of the [array] object. However, some of them
>> depend on
>> > > zexy externals (I hope I didn't miss any other dependencies). I
>> haven't
>> > > shared them yet so the documentation is quite poor (no help files,
>> docs
>> > > inside the abstraction) and they look a bit messy. But maybe you can
>> get
>> > > some inspiration for your library...
>> > > https://www.dropbox.com/s/xvj031korqw8guf/ctab-abs.zip?dl=0
>> > >
>> > > Additionally I've been working on three basic abstractions for
>> creating,
>> > > setting and reading multi-dimensional arrays of any number of
>> dimensions.
>> > > They are pure vanilla style and even come with a help file :-D.  (a
>> object
>> > > for array resizing is yet to be done...)
>> > > https://www.dropbox.com/s/6xfgdyt697138e6/carray.zip?dl=0
>> > >
>> > > Would be cool to hear your opinion on the multi-dimensional array
>> stuff!
>> > >
>> > > Christof
>> > >
>> > >
>> > >
>> > >
>> > > *Gesendet:* Samstag, 03. Oktober 2015 um 22:32 Uhr
>> > > *Von:* "Matt Barber" <brbrofsvl at gmail.com>
>> > > *An:* "IOhannes m zmölnig" <zmoelnig at iem.at>
>> > > *Cc:* Pd-List <pd-list at lists.iem.at>
>> > > *Betreff:* Re: [PD] array-abs
>> > > Thanks.
>> > >
>> > > Yes. Right now I'm just looking to see if these would be useful, if
>> > > there's anything awful about the syntax, if they try to do too much
>> or are
>> > > too fussy, if anyone would want to contribute, etc. When I get them
>> > > polished a bit I'll do a regular release on the normal channels (I
>> can't
>> > > remember if I have access to anything officially Pd related).
>> > >
>> > > Matt
>> > >
>> > > On Sat, Oct 3, 2015 at 4:22 PM, IOhannes m zmölnig <zmoelnig at iem.at>
>> > > wrote:
>> > >>
>> > >> hi,
>> > >>
>> > >> great!
>> > >>
>> > >> On 10/03/2015 07:36 PM, Matt Barber wrote:
>> > >> >
>> > >> > https://www.dropbox.com/s/45tk62dpz0z2mqo/array-abs.zip?dl=0
>> > >> >
>> > >>
>> > >> db?
>> > >>
>> > >> would you like to put those on a version control system of sorts,
>> e.g.
>> > >> the puredata svn or some publicly available git repository (e.g.
>> github)?
>> > >>
>> > >> (read as: please let us not go back to the dark ages, where code was
>> > >> shared by sending files around by on floppy disks and you never new
>> > >> which version was the current one)
>> > >>
>> > >> fgmards
>> > >> IOhannes
>> > >>
>> > >>
>> > >>
>> > >> _______________________________________________
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>> > >
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>
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