By using dplyr and rleid from data.table
library(data.table)
library(dplyr)
a=c(1,1,0,0,1,2,0,0)
df=data.frame(number=c(1,1,0,0,1,2,0,0))
df$Id=data.table::rleid(df$number)
df$rowname=seq(1:length(a))
df%>%group_by(Id,number)%>%summarise(start=first(rowname),end=last(rowname))%>%arrange(number)
# Groups: Id [5]
Id number start end
1 2 0 3 4
2 5 0 7 8
3 1 1 1 2
4 3 1 5 5
5 4 2 6 6
