### Exercise box pairing unpairing - two approaches

# preliminaries - get list of bases that are pairing and which unpairing
types<-"PPPPPUUUUPPPPPPPUPPUUUPPPPUUUUUUUUUUPPPPPPUUUUU"


U<-which(unlist(strsplit(types,""))=="U")
P<-which(unlist(strsplit(types,""))=="P")

Pgroups<-split(P, cumsum(c(1, diff(P) != 1)))
Ugroups<-split(U, cumsum(c(1, diff(U) != 1)))

# Simple answer
temp<-NULL
for(i in 1:length(Pgroups)){
temp<-c(temp,paste(range(Pgroups[i]),collapse="-"))
}
pairing<-paste(temp,collapse=", ")
pairing
#[1] "1-5, 10-16, 18-19, 23-26, 37-42"

temp<-NULL
for(i in 1:length(Ugroups)){
temp<-c(temp,paste(range(Ugroups[i]),collapse="-"))
}
unpairing<-paste(temp,collapse=", ")
unpairing
#[1] "6-9, 17-17, 20-22, 27-36, 43-47"