Question

Here is my plot

dat <- data.frame(
  pos = c(1, 3, 5, 8, 10, 12),
  start = c(1,3, 6, 7, 10, 11),
  end = c(5, 6, 9, 9, 13, 12)
)

library(ggplot2)
p <- ggplot(dat) + geom_segment(aes(x=start, y=pos, xend=end, yend=pos), 
       color="blue", size=2) + ylab("Fragments)") +  xlab("Position")
    scale_y_reverse() + theme_bw()

p1 <- p + opts(legend.position="left",
        panel.background=theme_blank(),panel.border=theme_blank(),
        panel.grid.major=theme_blank(),
        panel.grid.minor=theme_blank(),plot.background=theme_blank())


p1

Bitmapped desired version is, with axis line and labels near the segments. [ just exta-note: Note that bitmap changed the line to round ended (it would be interesting to see if we can do in the ggplot2)]

Answer 1

Interestingly, I actually think this is easier in base graphics:

plot(c(0,13),c(1,12),type = "n",axes = FALSE,xlab = "Position",ylab = "")
segments(x0 = dat$start,
         y0 = dat$pos,
         x1 = dat$end,
         y1 = dat$pos,
         col = "blue",
         lwd = 6,
         lend = 2)
text(x = dat$start - 0.5,y = dat$pos,labels = dat$pos,font = 2)
axis(1)
axis(1,at = c(0,12),labels = FALSE,tcl = 0.5)

Edit Added additional axis call to get the outer most tick in both directions.