Extracting pitch of first note, then assign duration

[Matthew Fong]

Hello everyone,

I am in the process of writing a note replacement function that allows me to place a custos anywhere I might need.

I am stuck on writing a function that extracts the pitch of the first note, given a list of notes, and then forcing a duration of 1/4. Any pointers would be appreciated.

For example given the list of notes below, I would like a function to output c4.

{

  \clef treble

  c2 d e f

  g4 a b c

}

Many thanks,

mattfong