[R] Running stats on individual data.frames from the split() function list

[Eric Vander Wal]

Hello, and thanks in advance.

I have a data.frame from which I want to count observations that occur 
on each day and determine the mean and std.error of said counts.

For instance:

x<-split(my.df, my.df$julian.days)

Although I'm still in my R learning infancy I am under the impression 
that x is a list of data.frames subsetting my.df by group 
(i.e.,julian.day) where day 1:366 are x$'1': x$'366' and my variables 
are x$'1'$var1, x$1$var2, for each data.frame in the list.

The data I seek can be supplied by

mean(sapply(split(x$'1'$var1, x$'1'$var2), length)) and 
std.error(sapply(split(x$'1'$var1, x$'1'$var2), length)), etc.

Is there an efficient means for me to process the entire list x so that 
I needn't call each data.frame (i.e., day) from list x individually?  No 
doubt there is a more sophisticated way to obtain this information from 
the outset, but I'm not yet familiar with it.

Thanks again for all the help,
Eric

-- 
Eric Vander Wal
Ph.D. Candidate
University of Saskatchewan, Department of Biology,
112 Science Place, Saskatoon, SK., S7N 5E2

"Pluralitas non est ponenda sine neccesitate"