Basic Vocabulary: Generating values
Before getting to the really cool things patterns can do, we need to build up a basic vocabulary. We'll start with some words, then move into phrases in the next tutorial.
Some of the patterns will be demonstrated with a Pbind construct. This is a taste of things to come -- sequencing sonic events using patterns. Don't worry about how Pbind works just yet... all in good time.
Let's start with a very quick reference of some basic patterns. More complete descriptions follow this list. The list might seem long at first, but concentrate your attention on patterns marked with a star. Those are the most basic, and commonly used. Again, the purpose is to start learning the vocabulary of patterns -- like learning new words when studying a human language.
This document describes a lot of patterns, but what I call "primary patterns" are the most important. If you are new to patterns, concentrate on these first. You can always come back and look at the rest later.
For more information on any of these patterns, select the class name and use the help key for your editor to open its help file.
Quick reference
Primary Patterns
Additional List Patterns
Additional Random Number Generators
Functional descriptions of patterns
List Patterns
The most obvious thing one would want to do with a pattern is to give it a list of values and have it read them out in order. You have a couple of choices, which differ in their handling of the 'repeats' parameter.
Pseq(list, repeats, offset): Play through the entire list 'repeats' times.
Pser(list, repeats, offset): Play through the list as many times as needed, but output only 'repeats' items.
Pseq(#[1, 2, 3], 4).asStream.all; // 12 items = 4 repeats * 3 items
Pser(#[1, 2, 3], 4).asStream.all; // 4 items only
Pseq is an obvious choice for streaming out known pitch and rhythm values.
Before playing a Pbind pattern such as this, make sure the server is booted.
s.boot;
(
p = Pbind(
\degree, Pseq(#[0, 0, 4, 4, 5, 5, 4], 1),
\dur, Pseq(#[0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 1], 1)
).play;
)
To stop the examples in this file, use the "stop" keyboard shortcut (cmd-. on Mac OSX, alt-. on Windows, check documentation for other editors). Or:
p.stop;
A variation, Pslide, plays overlapping segments of the input list.
Pslide(list, repeats, len, step, start, wrapAtEnd)
repeats: number of segments
len: length of each segment
step: is how far to step the start of each segment from previous.
start: what index to start at.
wrapAtEnd: if true (default), indexing wraps around if goes past beginning or end. If false, the pattern stops if it hits a nil element or goes outside the list bounds.
If step == 1, then the first segment is at 'start', the second at 'start' + 1, and so on.
Pslide(#[1, 2, 3, 4, 5, 6, 7, 8], 10, 3, 1, 0, false).asStream.all;
// or, to show the segments as separate arrays
Pslide(#[1, 2, 3, 4, 5, 6, 7, 8], 10, 3, 1, 0, false).clump(3).asStream.all;
// Flock of Seagulls!
(
p = Pbind(
\degree, Pslide((-6, -4 .. 12), 8, 3, 1, 0),
\dur, Pseq(#[0.1, 0.1, 0.2], inf),
\sustain, 0.15
).play;
)
Random-order list patterns
Prand(list, repeats): Choose items from the list randomly (same as list.choose).
// Prand: given scale degrees (pentatonic) with equal probability of each
(
p = Pbind(
\degree, Prand([0, 1, 2, 4, 5], inf),
\dur, 0.25
).play;
)
Pxrand(list, repeats): Choose randomly, but never repeat the same item twice in immediate succession.
// Pxrand: same as above but never repeats a pitch twice in a row
(
p = Pbind(
\degree, Pxrand([0, 1, 2, 4, 5], inf),
\dur, 0.25
).play;
)
Pshuf(list, repeats): Shuffle the list in random order, and use the same random order 'repeats' times. Like list.scramble.
// Pshuf: randomly ordered once and repeated
(
p = Pbind(
\degree, Pshuf([0, 1, 2, 4, 5], inf),
\dur, 0.25
).play;
)
Pwrand(list, weights, repeats): Choose randomly, according to weighted probabilities (same as list.wchoose(weights)).
// Pwrand: these probabilities favor triadic notes from scale degrees
(
p = Pbind(
\degree, Pwrand((0..7), [4, 1, 3, 1, 3, 2, 1].normalizeSum, inf),
\dur, 0.25
).play;
)
Pwalk(list, stepPattern, directionPattern, startPos): Random walk over the list. This pattern is a bit more complicated; see its help file for details.
Interlacing values and making arrays
These are opposing operations: interlacing means splitting arrays and merging them into a stream of single values, and arrays can be made out of single-value streams as well.
Place(list, repeats, offset): Take one from each item in the main array item in succession. Hard to explain, easier to see:
Place([0, [1, 2], [3, 4, 5]], 3).asStream.all;
--> [ 0, 1, 3, 0, 2, 4, 0, 1, 5 ]
If we turn this into a matrix and read vertically, the original arrays are clearly visible:
Place([0, [1, 2], [3, 4, 5]], 3).clump(3).do(_.postln);
[ 0, 1, 3 ] // leftmost column: 0 from first Place item
[ 0, 2, 4 ] // second column: alternates between 1 and 2, from second Place item
[ 0, 1, 5 ] // third column: 3, 4, 5 from third Place item
Ppatlace(list, repeats, offset): Take one value from each sub-pattern in order.
// Hanon exercise
(
p = Pbind(
\degree, Ppatlace([
Pseries(0, 1, 8), // first, third etc. notes
Pseries(2, 1, 7) // second, fourth etc. notes
], inf),
\dur, 0.25
).play;
)
That's also a taste of things to come: Patterns can be nested.
Ptuple(list, repeats): Get one value from each item in the array, and return all of them as an array of values.
// Chords
// \degree receives [7, 9, 4], then [6, 7, 4] successively, expanded to chords on the server
(
p = Pbind(
\degree, Ptuple([
Pseries(7, -1, 8),
Pseq([9, 7, 7, 7, 4, 4, 2, 2], 1),
Pseq([4, 4, 4, 2, 2, 0, 0, -3], 1)
], 1),
\dur, 1
).play;
)
Generating values
Arithmetic and geometric series
Now, let's move to patterns that produce values mathematically, without using a predefined list.
Pseries(start, step, length): Arithmetic series, successively adding 'step' to the starting value, returning a total of 'length' items.
Pgeom(start, grow, length): Geometric series, successively multiplying the current value by 'grow'.
// Use Pseries for a scale and Pgeom for an accelerando
(
p = Pbind(
\degree, Pseries(-7, 1, 15),
\dur, Pgeom(0.5, 0.89140193218427, 15)
).play;
)
Third-party extension alert: If you want an arithmetic or geometric series to start at one number and end at another specific number, the step size/multiplier must be calculated from the endpoints and the number of items desired. The ddwPatterns quark includes a convenience method, fromEndpoints, for both Pseries and Pgeom that performs this calculation. It's necessary to give an exact number of repeats, at least two and less than infinity.
p = Pgeom.fromEndpoints(0.5, 0.1, 15); // error if ddwPatterns not installed
p.postcs;
Prints:
Pgeom(0.5, 0.89140193218427, 15)
Random numbers and probability distributions
To see a distribution, make a histogram out of it.
Pmeanrand(0.0, 1.0, inf).asStream.nextN(10000).histo(200, 0.0, 1.0).plot;
Catchall Patterns
Not everything is pre-written as a pattern class. These patterns let you embed custom logic.
Pfunc(nextFunc, resetFunc): The next value is the return value from evaluating nextFunc. If .reset is called on a stream made from this pattern, resetFunc is evaluated. The stream will run indefinitely until nextFunc returns nil.
Pfuncn(func, repeats): Like Pfunc, output values come from evaluating the function. Pfuncn, however, returns exactly 'repeats' values and then stops. The default number of repeats is 1.
Proutine(routineFunc): Use the routineFunc in a routine. The stream's output values are whatever this function .yields. Proutine ends when it yields nil.
Next, we'll look at the central pattern for audio sequencing: Pbind.
Previous: PG_01_Introduction
Next: PG_03_What_Is_Pbind