[R] multiple plots using a loop

[Iain Gallagher]

Hi Darcy

This works for me:

Factor <- rep(factor(letters[1:4]), each = 10)
Size <- runif(40) * 100

par(mfrow = c(2, 2))

for (i in unique(Factor)) {
hist(Size[Factor == i], main = i,
xlab = paste("n =",length(Size[Factor == i])), ylab = "")
}
 
I think that using for (i in Factor) cycles through every occurrence of a level and so you only get four plots of the last level rather than a plot for every level.

cheers

iain

--- On Mon, 21/2/11, Darcy Webber <darcy.webber at gmail.com> wrote:

> From: Darcy Webber <darcy.webber at gmail.com>
> Subject: [R] multiple plots using a loop
> To: r-help at r-project.org
> Date: Monday, 21 February, 2011, 9:25
> Dear R users,
> 
> I am trying to write myself a loop in order to produce a
> set of 20
> length frequency plots each pertaining to a factor level. I
> would like
> each of these plots to be available on the same figure, so
> I have used
> par(mfrow = c(4, 5)). However, when I run my loop below, it
> produces
> 20 plots for each factor level and only displays the last
> factor
> levels LF plots. I'm fairly new to loops in R, so any help
> would be
> greatly appreciated.
> 
> I have provided an example data set below if required with
> just 4
> factors and adjusted par settings accordingly.
> 
> Factor <- rep(factor(letters[1:4]), each = 10)
> Size <- runif(40) * 100
> 
> par(mfrow = c(2, 2))
> 
> for (i in Factor) {
> LFchart <- hist(Size[Factor == i], main = i,
> xlab = c("n =",length(Size[Factor == i])), ylab = "")
> }
> 
> P.S. Also just a quick annoying question. My xlab
> displays:
> n =
> 120
> I would like it to display:
> n = 120
> but just cant get it to work. Any thoughts.
> 
> Regar
> 
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