On 05/09/11 21:26, Deepayan Sarkar wrote:
<SNIP>
1. The `official' way to get panel arguments is trellis.panelArgs(); e.g.,
p<- histogram(~rnorm(100) | gl(2, 50), type = "density")
str(trellis.panelArgs(p, 2))
List of 5
$ x : num [1:50] 0.277 1.144 1.13 -0.912 -0.892 ...
$ breaks : num [1:9] -2.561 -1.979 -1.398 -0.816 -0.234 ...
$ type : chr "density"
$ equal.widths: logi TRUE
$ nint : num 8
2. hist.constructor() is needed for technical reasons, and can be
considered to be the same as hist() for this purpose. So the
computations performed by panel.histogram() can be reduced to
histogram.computations<-
function(x, breaks, equal.widths = TRUE,
type = "density", nint, ...)
{
if (is.null(breaks))
{
breaks<-
if (is.factor(x)) seq_len(1 + nlevels(x)) - 0.5
else if (equal.widths) do.breaks(range(x, finite = TRUE), nint)
else quantile(x, 0:nint/nint, na.rm = TRUE)
}
hist(x, breaks = breaks, plot = FALSE)
}
which may be used as follows to get the ``actual data defining the histogram'':
a<- trellis.panelArgs(p, 2)
h<- do.call(histogram.computations, a)
str(h)
List of 7
$ breaks : num [1:9] -2.561 -1.979 -1.398 -0.816 -0.234 ...
$ counts : int [1:8] 1 4 6 14 7 8 6 4
$ intensities: num [1:8] 0.0344 0.1375 0.2062 0.4812 0.2406 ...
$ density : num [1:8] 0.0344 0.1375 0.2062 0.4812 0.2406 ...
$ mids : num [1:8] -2.2704 -1.6885 -1.1065 -0.5246 0.0573 ...
$ xname : chr "x"
$ equidist : logi TRUE
- attr(*, "class")= chr "histogram"
As usual: Clear, concise, and useful! Thanks!
cheers,
Rolf
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