R help - Apr 2005 - Automating plot labelling in custom function in lapply() ?

Dear List,

Consider the following example:

dat <- data.frame(var1 = rnorm(100), var2 = rnorm(100),
                   var3 = rnorm(100), var4 = rnorm(100))
oldpar <- par(mfrow = c(2,2), no.readonly = TRUE)
invisible(lapply(dat,
                  function(x) {
                    plot(density(x),
                         main = deparse(substitute(x))) }
                  )
           )
par(oldpar)

I want to the main title in each of the density plots to be var1, var2, 
etc. The above code produces x[[1]], x[[2]] etc.

What do I need to modify to be able to use the name of x as the plot 
label within in the above situation?

Thanks in advance,

Gav
-- 
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Gavin Simpson                     [T] +44 (0)20 7679 5522
ENSIS Research Fellow             [F] +44 (0)20 7679 7565
ENSIS Ltd. & ECRC                 [E] gavin.simpsonATNOSPAMucl.ac.uk
UCL Department of Geography       [W] http://www.ucl.ac.uk/~ucfagls/cv/
26 Bedford Way                    [W] http://www.ucl.ac.uk/~ucfagls/
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On Fri, 2005-04-29 at 13:00 +0100, Gavin Simpson wrote:
> Dear List,
> 
> Consider the following example:
> 
> dat <- data.frame(var1 = rnorm(100), var2 = rnorm(100),
>                    var3 = rnorm(100), var4 = rnorm(100))
> oldpar <- par(mfrow = c(2,2), no.readonly = TRUE)
> invisible(lapply(dat,
>                   function(x) {
>                     plot(density(x),
>                          main = deparse(substitute(x))) }
>                   )
>            )
> par(oldpar)
> 
> I want to the main title in each of the density plots to be var1, var2, 
> etc. The above code produces x[[1]], x[[2]] etc.
> 
> What do I need to modify to be able to use the name of x as the plot 
> label within in the above situation?
> 
> Thanks in advance,
> 
> Gav
Gavin,

To paraphrase John Fox from a recent thread, "this is one of those times
where trying to avoid using a for() loop is counterproductive":

oldpar <- par(mfrow = c(2,2), no.readonly = TRUE)

for (i in 1:4)
{
  plot(density(dat[, i]), main = colnames(dat)[i])
}

par(oldpar)


HTH,

Marc Schwartz

Gavin Simpson wrote on 4/29/2005 5:00 AM:
> Dear List,
> 
> Consider the following example:
> 
> dat <- data.frame(var1 = rnorm(100), var2 = rnorm(100),
>                   var3 = rnorm(100), var4 = rnorm(100))
> oldpar <- par(mfrow = c(2,2), no.readonly = TRUE)
> invisible(lapply(dat,
>                  function(x) {
>                    plot(density(x),
>                         main = deparse(substitute(x))) }
>                  )
>           )
> par(oldpar)
> 
> I want to the main title in each of the density plots to be var1, var2, 
> etc. The above code produces x[[1]], x[[2]] etc.
> 
> What do I need to modify to be able to use the name of x as the plot 
> label within in the above situation?
> 
> Thanks in advance,
> 
> Gav
Gav,

I think a `for' loop would be more useful here (not to mention, more 
readable):

dat <- data.frame(var1 = rnorm(100), var2 = rnorm(100),
                   var3 = rnorm(100), var4 = rnorm(100))
oldpar <- par(mfrow = c(2,2), no.readonly = TRUE)
for(v in names(dat))
   plot(density(dat[[v]]), main = v)
par(oldpar)

HTH,

--sundar