Plot histograms as lines

Question

I want to plot several histograms of time data (1 week long) on the same plot as lines.

I have time data:

> dput(head(ts))
structure(c(1364421605.227, 1364375025.034, 1364376298.393, 1364375002.928, 
1364393158.084, 1364423268.856), class = c("POSIXct", "POSIXt"))

and I want to plot its histogram. hist(ts,breaks=7*24) works fine, but it uses the h plot type which will obscure other histogram plots I want to add (I know I can use transparent colors - rainbow with alpha=0.5, but I really want to see the lines).

I tried

> hist(ts, breaks = 7*24, type="l")
Warning messages:
1: In title(main = main, sub = sub, xlab = xlab, ylab = ylab, ...) :
  graphical parameter "type" is obsolete
Calls: hist -> hist.POSIXt -> myplot -> plot -> plot.histogram -> title
2: In axis(2, ...) : graphical parameter "type" is obsolete
Calls: hist -> hist.POSIXt -> myplot -> axis
3: In axis(side, at = z, labels = labels, ...) :
  graphical parameter "type" is obsolete
Calls: hist -> hist.POSIXt -> myplot -> axis.POSIXct -> axis

why is hist passing type to title?

I can create the histogram object and plot it separately:

> h <- hist(ts, breaks=7*24, plot=FALSE)
> plot(x=h$mids, y=h$density, type="l")

but then the x axis is labeled with numbers (e.d., "1364421605") not dates (e.g., "Mar 25").

I guess I am supposed to use axis, but I would rather not handle that myself - after all, hist constructs just the axis I want!

Thanks!

Answer 1

The following looks weird because you only gave us six data points in your dput. You can plot a line plot without the x-axis and add it afterwards like so:

h <- hist(ts, breaks=7*24, plot=FALSE)
plot(x=h$mids, y=h$density, type="l", xaxt="n")
axis(1,at=ts,labels=format(ts,"%b-%d"))