Algorithm challenge: piano roll mapping based on configurable note pool


#1

Hi there,

I’m quite new to coding and am stuck on a solution and I thought might be a good opportunity for someone smarter than I am to show me how less smarter than them I am, ha.

Basically, I would like to map a piano roll based on user defined notes, we’ll call this our notePool rather than a scale since it can be any arrangement of notes.

NotePool rules.

  • These notes are stored in a StringArray, e.g. “C”, “Db” “D” “E”, etc.
  • This notePool is a sorted set (no duplicates) and always starts at C.
  • The strings in the pool do not include octave numbers.

PianoRoll rules

  • The pianoRoll’s middle note is defined by a rootNote string.
  • The pianoRoll is scrollable so this rootNote includes an octave number, like all other notes of course.

Example:
If my notePool is “C”, “D”, “E”, my pianoRoll rootNote is “D3”, and has 7 notes. The resulting pianoRoll from bottom to top should be “D2”, “E2”, “C3”, “D3”, “E3”, “C4”, “D4”.

Problems:
In my attempt, I’m finding it difficult to get the octave numbers to be sorted like above, e.g. my solution is like above but the 2’s are 3’s…
Bonus problem: what if the given rootNote is not in the notePool? How to find the “nearest” note in the pool?

Of course I’m not expecting a full solution, but any thoughts on possible tried and true approaches or direction I can follow from someone experienced would be greatly appreciated.

Many thanks for your time and help!


#2

never mind I have it. The trick was using % poolSize for the note numbers and then / poolSize for the octave numbers.