Change how random numbers are chosen

use_random_source  noise_type (symbol)

Sets the random number source to be one of :white, :pink, :light_pink, :dark_pink or :perlin.

:white is totally random - between 0 and 1, you can expect an even spread of values around 0.1, 0.2, 0.3 etc. This means that jumping around within the range (including large jumps) is expected.

:pink is more likely to produce values in the middle of the range and less likely to produce values at the extremes. Between 0 and 1 you expect to see a concentration of values around 0.5. This can make random melodies a little bit more smooth.

:perlin is a special kind of noise which produces gradients, a bit like a mountain landscape. Large jumps are much less likely and you will tend to see lots of smooth motion going either up or down

:light_pink is halfway between white noise and pink noise - more random and jumpy

:dark_pink is halfway between pink noise and brown noise - less jumpy with smoother slopes

You can see the ‘buckets’ that the numbers between 0 and 1 fall into with the following code:

    rand_type :white
    puts 10000.times.collect { rand.round(1) }.tally.sort
    rand_type :pink
    puts 10000.times.collect { rand.round(1) }.tally.sort
    rand_type :perlin
    puts 10000.times.collect { rand.round(1) }.tally.sort

Introduced in v3.3

Example

# Example 1

use_random_source :white
  rand_reset
  puts rand
  puts rand
  puts rand
  rand_reset
  use_random_source :pink
  puts rand
  puts rand
  rand_reset
  use_random_source :perlin
  puts rand
  puts rand
  with_random_source :white do
    puts rand
  end
  puts rand

# use white noise as the distribution (default)
# reset random seed
# => 0.75006103515625
# => 0.733917236328125
# => 0.464202880859375
# reset it again
# use pink noise as the distribution
# => 0.47808837890625
# => 0.56011962890625
# reset it
# use perlin noise as the distribution
# => 0.546478271484375
# => 0.573150634765625
# use white noise just for this block
# => 0.464202880859375
 
# => 0.597015380859375
# notice how the last generator (perlin) is restored