[R] Plotting an array of histograms

[Mark Myatt]

Ted.Harding at nessie.mcc.ac.uk writes:
>I have a dataset (of say values of X), each value associated
>with a level of a factor F (25 levels in all), in a dataframe.
>
>I want to make a single plot which contains 25 histograms of X,
>one for each level of F and each one appropriately labelled.
>
>(And, since there are 25 levels, a 5x5 array would be nice).
>
>What's the trick in R, please?

The trick is to the par() function. Here is an example ...

        #
        # generate some dummy data
        #
        x <- rnorm(n = 1000, mean = 12, sd = 1)
        f <- round(runif(n = 1000, min = 1, max = 25))

        #
        # set device for 5 * 5 array of charts
        #
        par(mfrow = c(5,5))

        #
        # plot histograms
        #
        tapply(x, f, hist, ylab="n", xlab="x")

I think you'll need a for() loop to get better control over the plots.
Something like:

        for(i in min(f):max(f))
          {
          hist(x[f==i], xlim=range(x), ylab="n", xlab="x", main = i)
          }

But I might be wrong.

I hope that helps.

Mark



--
Mark Myatt


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