[PD] List with variable number of floats

Tue Aug 17 18:28:06 CEST 2010

Hi João,

On Tue, Aug 17, 2010 at 04:30:00PM +0100, João de Brito Rocha Reis Vidigal wrote:
> Here's what I wanna do:
> 
> I have 18 slot for audio and video to play. There can be one playing, none or even um to the 18.
> These slots are to be triggered randomly.
> Is there a possibility of storing the ID of the slots already triggered? Like a list? The thing is that if it is a list it would have to have a variable number of floats (wouldn't it?).
> Why do I need this? Because after triggering a random slot ON I want to trigger a random slot OFF. So, I have to know what are the slots triggered on in order to trigger one of these OFF and not one 18. Otherwise I could end up triggering off a slot that was never on!
> As well I need to know witch ones are OFF to randomly select and turn one on.

A brute-force approach to your problem is attached: It uses [select] to
re-trigger the random selection if you get a slot-value that already is off.
If instead you get a usable slot-value, it stores this in a [f] object
by using the cold, right inlet, so it can be switched off later, then
also updates the [select] via its right inlet to watch for the new "ON"
slot.

There is a small risk to get a lot of the same values from [random] but
this is very, very unlikely. 

You should remember the 

 [t f b]
  \/
  /\
 [f ]

idiom to delay the output of a float value by one execution step. It's
often useful, and also the use of [select] to filter out unwanted
values.

You can also do all this without storing the OFF value by transferring
the logic of switching off or on into your "slot" abstractions. The
c_tgl.pd abstractions shows how to do that. It compares an incoming
slot-number with [== $1] where $1 is the slot-id passed as argument. It
has a global receiver in it to simplify patching a bit.

Ciao 
-- 
Frank
-------------- next part --------------
#N canvas 84 0 1114 648 10;
#X obj 180 170 select 0;
#X obj 210 141 random 18;
#X floatatom 293 288 5 0 0 0 ON - -;
#X floatatom 231 288 5 0 0 0 OFF - -;
#X floatatom 252 166 5 0 0 0 - - -;
#X obj 293 315 hradio 15 1 0 18 empty empty empty 0 -8 0 10 -262144
-1 -1 13;
#X obj 294 339 hradio 15 1 0 18 empty empty empty 0 -8 0 10 -262144
-1 -1 5;
#X msg 210 112 bang;
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#X msg 340 391 1 1003-in1-\$1;
#X obj 231 429 unpack 0 s;
#X obj 231 455 send;
#X obj 376 107 u_robinpoly 18 c_tgl;
#X obj 888 45 c_tgl 0;
#X obj 888 75 c_tgl 1;
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#X obj 888 525 c_tgl 16;
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#X obj 363 286 send TOGGLE;
#X text 447 288 in c_tgl!!;
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#X connect 0 0 8 0;
#X connect 0 1 11 0;
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#X connect 11 0 10 1;
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#X connect 50 0 51 0;
#X connect 50 1 51 1;
-------------- next part --------------
#N canvas 0 0 453 340 10;
#X obj 130 113 tgl 15 0 0 0 empty 17 7 0 10 -262144 -1 -1 0 1;
#X obj 130 45 r TOGGLE;
#X obj 130 72 == \$1;
#X connect 1 0 2 0;
#X connect 2 0 0 0;
#X coords 0 -1 1 1 85 30 1 100 100;