Untitled

Plotting a line graph with vertical and horizontale segments
>Anna
    from     to      values
    5        10       34
   10       14       45
   14       23       46
   23       34       54

> mydata
  from to values
1    5 10     34
2   10 14     45
3   14 23     46
4   23 34     54

plot(NA,xlim=c(0,40),ylim=c(0,60))
points(values~from,data=mydata)
points(values~to,data=mydata)
segments(mydata$from,mydata$values,mydata$to,mydata$values)

# Sample data
n <- 10
instants <- c(0, cumsum(rexp(n)))
d <- data.frame(
  from = instants[1:n],
  to = instants[-1],
  value = cumsum(rnorm(n))
)

plot( c(d$from[1], d$to), c(d$value, d$value[n]), type="s" )