Random repetitions

In this example, we will use some of auxjad’s classes to generate random repeated measures.

First, we start by importing both abjad and auxjad.

>>> import abjad
>>> import auxjad

First, let’s create a container with an arbitrary rhythm. The pitches do not matter at this point since we will randomise them shortly.

>>> container = abjad.Container(
...     r"c'4-- c'8.-- c'16( c'8)-. c'8-. c'8-. r8"
... )
>>> abjad.show(container)

Next, let’s initialise auxjad.PitchRandomiser with this container as well as a list representing pitches. This will be the source for the random pitches selected by this randomiser.

>>> pitch_list = ["c'", "cs'", "d'", "ef'", "e'"]
>>> randomiser = auxjad.PitchRandomiser(container,
...                                     pitches=pitch_list,
...                                     )

Let’s now output a first group of two measures with random pitches using the method auxjad.PitchRandomiser.output_n().

>>> notes = randomiser.output_n(2)
>>> group_1 = abjad.Staff(notes)
>>> abjad.show(group_1)

Let’s now change the pitch list using the property pitches of the randomiser and create another group of measures.

>>> randomiser.pitches = ["a", "b", "bf'", "a''", "b''"]
>>> notes = randomiser.output_n(2)
>>> group_2 = abjad.Staff(notes)
>>> abjad.show(group_2)

Up to now, the pitches were being selected with equal weight (i.e. an uniform distribution). Changing the weights property to a list of int’s or float’s allow us to give more weight to certain pitches. It’s important that this list has the same length as the number of pitches in pitches.

>>> randomiser.weights = [6, 3, 2, 1, 1]

At this point, let’s also change the input container for the randomiser:

>>> container = abjad.Container(
...     r"\time 3/4 c'4--( ~ "
...     r"\times 4/5 {c'16 c'16-. c'16-. c'16-. c'16-.)} "
...     r"r8 c'8->"
... )
>>> abjad.show(container)

Now, with the new contents of the randomiser, let’s output two more measures as the third and final group of measures.

>>> randomiser.contents = container
>>> notes = randomiser.output_n(2)
>>> group_3 = abjad.Staff(notes)
>>> abjad.show(group_3)

We can now use auxjad.Repeater to create a staff made out of multiple repetitions of these three groups. When the repeater type is set to to 'volta' using the attribute repeat_type, it will output measures with repetition bar lines and with a written indication for the number of repeats. Let’s start with the first group and repeat it 3x.

>>> staff = abjad.Staff()
>>> repeater = auxjad.Repeater(group_1,
...                            repeat_type='volta',
...                            )
>>> notes = repeater(3)
>>> staff.append(notes)
>>> abjad.show(staff)

Let’s now do the same with the second group, repeating it 5x and appending it to our staff.

>>> repeater.contents = group_2
>>> notes = repeater(5)
>>> staff.append(notes)
>>> abjad.show(staff)

Finally, let’s do the same with the third group and repeat it 4x. This will be our final score.

>>> repeater.contents = group_3
>>> notes = repeater(4)
>>> staff.append(notes)
>>> abjad.show(staff)