Looping with auxjad.WindowLooper

In this next example, we will use some of auxjad’s classes to generate a container of randomly selected material, and then use this material as input for the looping and shuffling classes.

First, we start by importing both abjad and auxjad.

>>> import abjad
>>> import auxjad

Let’s start by deciding what random selectors will be responsible for generating each parameter of our basic material. Let’s use auxjad.TenneySelector for pitches, which is an implementation of Tenney’s Dissonant Counterpoint Algorithm; at each call, this algorithm prioritises elements that haven’t been select for the longest time. For the durations, dynamics, and articulations, the example will use auxjad.CartographySelector. Each element input into this type of selector has a probability of being selected which is dependent on its index. By default, the probability of consecutive elements decay with a rate of 0.75. For more information on both of these classes, check auxjad’s API page (link in the left panel).

>>> pitch_selector = auxjad.TenneySelector(["c'",
...                                         ("fs'", "g'"),
...                                         "ef''",
...                                         "a''",
...                                         ("b", "bf''"),
...                                         ])
>>> duration_selector = auxjad.CartographySelector([(2, 8),
...                                                 (3, 8),
...                                                 (5, 8),
...                                                 ])
>>> dynamic_selector = auxjad.CartographySelector(['p', 'mp', 'mf', 'f'])
>>> articulation_selector = auxjad.CartographySelector([None, '-', '>'])

Let’s now create eight random notes, each with four parameters randomly selected by the classes above.

>>> pitches = [pitch_selector() for _ in range(8)]
>>> durations = [duration_selector() for _ in range(8)]
>>> dynamics = [dynamic_selector() for _ in range(8)]
>>> articulations = [articulation_selector() for _ in range(8)]

With these list’s’ of pitches, durations, dynamics, and articulations, we can now use auxjad.LeafDynMaker to create the individual abjad leaves for us. It’s important to note that there is no time signature being imposed at this point, so LilyPond will fallback to a four by four when displaying the container below. This is not a problem since this will be used as the basic material for the looper, which will then automatically take care of time signatures.

>>> leaf_dyn_maker = auxjad.LeafDynMaker()
>>> notes = leaf_dyn_maker(pitches, durations, dynamics, articulations)
>>> container = abjad.Container(notes)
>>> abjad.show(container)

Let’s now use auxjad.WindowLooper to output loops of windows of the material. Let’s initiate this class with a window size of a 4/4 measure, and a step forward of a semiquaver. Setting after_rest to the duration (1, 4) will add crotchet rests in between consecutive outputs of this looper. Setting after_rest_in_new_measure to True ensure that these rests (which work as separators of consecutive windows) are in a new measure by themselves.

>>> looper = auxjad.WindowLooper(container,
...                              window_size=(4, 4),
...                              step_size=(1, 16),
...                              after_rest=(1, 4),
...                              after_rest_in_new_measure=True,
...                              )

We can now use the output_n() to output several measures of the looping process for us. In this case, let’s output four measures.

>>> staff = abjad.Staff()
>>> notes = looper.output_n(4)
>>> staff.append(notes)
>>> abjad.show(staff)

Let’s now change the values of step_size from a semiquaver into a crotchet and output four more measures.

>>> looper.step_size = (1, 4)
>>> notes = looper.output_n(4)
>>> staff.append(notes)
>>> abjad.show(staff)

Let’s now change both window_size and step_size as well as remove the after rests, and then output six more measures.

>>> looper.window_size = (7, 8)
>>> looper.step_size = (1, 16)
>>> looper.after_rest = 0
>>> notes = looper.output_n(6)
>>> staff.append(notes)
>>> abjad.show(staff)

Let’s now add this staff to an abjad.Score and call the method add_final_bar_line() which Auxjad adds to abjad.Score.

>>> score = abjad.Score([staff])
>>> score.add_final_bar_line()

The final result is shown below.

>>> abjad.show(score)