\version "2.10.25"

\header {
  title="Hiding choir staves with rests only (for some/all voices)"
}

\markup { \fill-line { 
\justify-string #"If you have a choir score where some voices are quit for a long time, you might want to hide staves with rests only. By default, lilypond will show all staves, even if they only contain rests. To change this, simply add the \\RemoveEmptyStaffContext to your \\layout. The first system would still show all staves for all voices. To force this setting to also apply to the first system of a score, set #'remove-first of VerticalAxisGroup to ##t. If only one staff is displayed, the choir bracket would also be hidden, so you will probably need to set #'collapse-height of SystemStartBracket to #1 (or anything smaller than 5, which is the usual number of lines in a staff). If you have some voices where you still want to display all (even empty) staves, you need to set the remove-empty property of the VerticalAxisGroup to true for that one staff only. You can do this in the \\with section of the staff (in this example, the alto staff will never erase empty lines, while the soprano staff will)." } }


sop = \relative c'' {
  R1*2 |\break 
  c4 c c c | R1 |\break
  R1*2 | \break
  R1*2 |\break 
  c4 c c c | R1 \bar"|."
}

alt = \relative c'' {
  g4 g g g | R1 | \break |
  R1*2 | \break
  R1*2 | \break
  g4 g g g | R1 | \break |
  g4 g g g | R1 \bar"|."
}

\layout {
  \context { 
    % add the RemoveEmptyStaffContext that erases rest-only staves
    \RemoveEmptyStaffContext 
  }
  \context {
    \Score
    % Remove all-rest staves also in the first system
    \override VerticalAxisGroup #'remove-first = ##t
  }
  \context {
    \ChoirStaff 
    % If only one non-empty staff in a system exists, still print the backet
    \override SystemStartBracket #'collapse-height = #1
  }
}

\score{
  \context ChoirStaff <<
    \context Staff=soprano <<
      \sop
      \set Staff.shortInstrumentName = "S"
    >>
    % never remove empty staves from the alto staff:
    \context Staff=alto \with { \override VerticalAxisGroup #'remove-empty = ##f }
    <<
      \alt
      \set Staff.shortInstrumentName = "A"
    >>
  >>
}