Sonic Pi random beat slicer/remixer

beat_slicer.rb

# Beat slicer
# Taking a sample, we can divide it into n slices 
# (in this example we'll use 16). Using the :start
# and :finish parameters for the sample method, we
# can 'remix' the sound by playing the slices in a 
# random order

sample_name = :loop_amen
n = 16.0
# start and finish range from 0 to 1
slice_dur = 1 / n
# to sleep for the right amount of time,
# we calculate a 16th of the sample_duration
sleep_dur = sample_duration(sample_name) / n

# First we work out an array of all the points between
# 0 and 1 to use for start times.
beat_points = (0..(n-1)).map { |i| i * slice_dur }
beat_points.concat([1]) # to get the last beat - will become clear later

# This gives us an array like so:
# [
#   0.0, 0.0625, 0.125, 0.1875, 0.25, 0.3125, 0.375, 
#   0.4375, 0.5, 0.5625, 0.625, 0.6875, 0.75, 0.8125, 
#   0.875, 0.9375, 1
# ]
#
# What we need is to pair each of these together to
# give us the start and finish times of each slice.
# Luckily this is exactly what Ruby's each_cons method does! 
start_and_end_times = beat_points.each_cons(2).to_a

# This means start_and_end_times is now an array like this:
#
# [[0.0, 0.0625], [0.0625, 0.125], [0.125, 0.1875], [0.1875, 0.25], 
# [0.25, 0.3125], [0.3125, 0.375], [0.375, 0.4375], [0.4375, 0.5], 
# [0.5, 0.5625], [0.5625, 0.625], [0.625, 0.6875], [0.6875, 0.75], 
# [0.75, 0.8125], [0.8125, 0.875], [0.875, 0.9375], [0.9375, 1]]
#
# So we have our start and end times for each of the 16 slices.
# NOTE the 1 at the end - that was added earlier to make sure
# we can play the last slice

random_beat_slices = start_and_end_times.shuffle
loop do
  random_beat_slices.each do |s_and_e|
    sample sample_name, attack: 0, release: 0.05, start: s_and_e.first, finish: s_and_e.last
    sleep sleep_dur
  end
end