Select Every Nth

from flpianoroll import *

note_ct = score.noteCount

def createDialog():
    form = ScriptDialog("Select every nth note","")
    form.AddInputKnobInt("nth",2,2,64)
    return form

def apply(form):
    nth = form.GetInputValue("nth")
    times = set()

    for n in range(note_ct):
        xnote = score.getNote(n)
        times.add(xnote.time)


    goodtimes = list()

    for n,t in enumerate(sorted(list(times))):
        if (n % nth) == 0:
            goodtimes.append(t)

    goodnotes = list()

    for n in range(note_ct):
        xnote = score.getNote(n)
        if xnote.time in goodtimes:
            goodnotes.append(n)

    for n in goodnotes:
        xnote = score.getNote(n)
        xnote.selected = True