hpv_neg <- hpv_neg <- read.delim("hpv_neg.bedgraph",skip=1,sep="\t",header=FALSE)
hpv_neg <- hpv_neg[!is.na(hpv_neg$V4),]
write.table(hpv_neg, file="dropped_hpv_neg.bedgraph",sep="\t",quote=FALSE,col.names = FALSE,row.names=FALSE)