Pwrand 

superclass: ListPatterns

returns one item from the list at random for each repeat, the probability

for each item is determined by a list of weights which should sum to 1.0.

(

var a, b;

a = Pwrand.new(#[1, 2, 3], #[1, 3, 5].normalizeSum, 6); // return 6 items

b = a.asStream;

7.do({ b.next.postln; });

)

Prand used as a sequence of pitches:

(

SynthDef("help-sinegrain", 

{ arg out=0, freq=440, sustain=0.05;

var env;

env = EnvGen.kr(Env.perc(0.01, sustain, 0.2), doneAction:2);

Out.ar(out, SinOsc.ar(freq, 0, env))

}).send(s);

)

(

a = Pwrand(#[60, 61, 63, 65, 72], #[10, 2, 3, 1, 3].normalizeSum, inf).asStream;

Routine({

loop({

Synth("help-sinegrain", [\freq, a.next.midicps]);

0.1.wait;

})

}).play;

)