Transcript=c(1,1,1,1,2,2,2,2,2)
Exon=rep(c(1:4,1:5))
S=c("aaa","ttt","ccc","ggg","ata","tat","cgc","gcg","bbb")
E=c("AAA","TTT","CCC","GGG","ATA","TAT","CGC","GCG","BBB")
DF=data.frame(Transcript,Exon,SequenceStart,SequenceEnd)
DF
s=split( DF , DF$Transcript,)