x = structure(list(ID = 1, AF1MEDIDA1 = 11.7, AF1MEDIDA2 = 5, AF2MEDIDA1 = 21,

AF2MEDIDA2 = 21, AF3MEDIDA1 = 33, AF3MEDIDA2 = 20.03), .Names = c("ID",

"AF1MEDIDA1", "AF1MEDIDA2", "AF2MEDIDA1", "AF2MEDIDA2", "AF3MEDIDA1",

"AF3MEDIDA2"), row.names = c(NA, -1L), class = "data.frame")

y = with(reshape(x, varying=2:7, idvar="ID", direction="long", sep="", timevar="Grupo", ),

data.frame(ID=ID,

REP=substr(Grupo, 2, nchar(Grupo)),

AF=paste("AF", substr(Grupo, 1, 1), sep=""),

VALOR=AF))