Deleting notes in Reascript using Lua interesting question...

[Superpuman]

Ok - let's say I have a lot of notes in my midi track.
I have 300 notes and now I have calculated that I want
to delete all notes from 150 to 175.

If I use reaper.MIDI_deleteNote(take,150)
this will delete note 150 - so far so good !

After that I write reaper.MIDI_deleteNote(take,151)
and that code will delete the wrong note and I understad
why - because I deleted note 150 before so the note that
I now want to delete - note 151 - has now index 150....

So....if I want to delete note 150 to 175 i would write
a loop that deletes note 150 25 times ( or 26 to be correct).

But...maybe I wanted to delete note 150,157,162,169,173....you get the picture....

So..finally....my question.....Is there a better way of handling
deleting notes at special positions in the grid ?

Kind Regards

[schwa]

This is a standard programming idiom. Either decrement the loop variable every time you delete an item, or loop from back to front.

for i=0,cnt-1 do
  if WantDelete(i) then
    reaper.MIDI_DeleteNote(take,i)
    i=i-1
  end
end

... or ...

for i=cnt-1,0 do
  if WantDelete(i) then    
    reaper.MIDI_DeleteNote(take,i)  
  end
end

[Superpuman]

Originally Posted by schwa

This is a standard programming idiom. Either decrement the loop variable every time you delete an item, or loop from back to front.

for i=0,cnt-1 do
  if WantDelete(i) then
    reaper.MIDI_DeleteNote(take,i)
    i=i-1
  end
end

... or ...

for i=cnt-1,0 do
  if WantDelete(i) then    
    reaper.MIDI_DeleteNote(take,i)  
  end
end

From back to front -Thank you ! Nice soluton !

[Lawrence]

Originally Posted by schwa

This is a standard programming idiom.

It is.

The other option, depending on the collection or array or language methods, etc, etc, is to remove the range of items all at once. No idea if whatever he used there, Lua or JS or whatever allows that or not, making "selections" of multiple things in a collection, then deleting all "selected" items.

[_Stevie_]

I'm confronted with the same problem and I'm literally desperate. I tried pretty much everything, but my code just doesn't seem to work.

The script is supposed to delete all MIDI notes before the edit cursor. A version where all notes get selected already works.
The problems seem to happen in the undo block. I tried the "loop back to front" but nothing happens at all.

for i = 0, reaper.CountSelectedMediaItems(0)-1 do -- loop through all selected items
    item = reaper.GetSelectedMediaItem(0, i)
    if i > 0 then
        reaper.ShowMessageBox("Please select only one item", "Error" , 0) -- popup error message, if more than 1 item is selected
        return
    else
        for t = 0, reaper.CountTakes(item)-1 do -- Loop through all takes within each selected item
            take = reaper.GetTake(item, t)
            if reaper.TakeIsMIDI(take) then -- make sure, that take is MIDI
                cursor_position = reaper.GetCursorPosition()  -- get edit cursor position 
                cursor_position_ppq = reaper.MIDI_GetPPQPosFromProjTime(take, cursor_position) -- convert to PPQ
                notes = reaper.MIDI_CountEvts(take) -- count notes and save amount to "notes"
            end
        end
    end 
end

reaper.Undo_BeginBlock() reaper.PreventUIRefresh(1)

for n = notes-1, 0 do -- loop thru all notes
    _, sel, _, start_note, end_note, _, _, _ = reaper.MIDI_GetNote(take, n) -- get selection status, start and end position
    
    if start_note < cursor_position_ppq and end_note <= cursor_position_ppq then 
    reaper.MIDI_DeleteNote(take, n) -- delete note if condition above is true

    
    end
end


reaper.PreventUIRefresh(-1) reaper.Undo_EndBlock('Delete notes before cursor', 2)

[juliansader]

* To loop backwards, tell Lua to use "-1" steps:, for n = notes-1, 0, -1 do

* Move the "for n = notes-1, 0, -1 do" loop to within the "for t = 0, reaper.CountTakes(item)-1 do" loop, otherwise the script will only edit the last take in the item.

[_Stevie_]

Ahhh thanks so much Julian! It works!
Actually the script should only work with one item selected,
would I still need to put the loop inside the CountTakes loop?