Hi, Don:
Thanks for your suggestion to use "do.call" in my "get.Index". I
discovered that your version actually produces cosmetically different
answers in R 1.6.3 and S-Plus 6.1 for Windows. Fortunately, in the
context, this difference was unimportant. Since yours is faster, it is
clearly
Thanks to Thomas Lumley, Sundar Dorai-Raj, and Don McQueen for their
suggestions. I need the INDICES as part of the output data.frame, which
McQueen's solution provided. I generalized his method as follows:
by.to.data.frame <-
function(x, INDICES, FUN){
# Split data.frame x on x[,INDICES]
# an
Since I don't have your by.df to test with I may not have it exactly
right, but something along these lines should work:
byFits <- lapply(split(by.df,paste(by.df$A,by.df$B)),
FUN=function(data.) {
tmp <- coef(lm(y~x,data.))
data.frame(A=uni
Hi, Thomas, et al.:
Thanks for the reply. Unfortunately, "do.call" strips off the subset
identifiers, which I want to use for further modeling:
> do.call("rbind", byFits)
(Intercept) x
[1,] 0.333 -1.517960e-016
[2,] 0.667 3.282015e-016
The following does what I wa
On Thu, 5 Jun 2003, Spencer Graves wrote:
> Dear R-Help:
>
> I want to (a) subset a data.frame by several columns, (b) fit a model
> to each subset, and (c) store a vector of results from the fit in the
> columns of a data.frame. In the past, I've used "for" loops do do this.
> Is there
Dear R-Help:
I want to (a) subset a data.frame by several columns, (b) fit a model
to each subset, and (c) store a vector of results from the fit in the
columns of a data.frame. In the past, I've used "for" loops do do this.
Is there a way to use "by"?
Consider the following example:
Spencer,
Would "sapply" be better here?
R> by.df <- data.frame(A=rep(c("A1", "A2"), each=3),
R+ B=rep(c("B1", "B2"), each=3),
R+ x=1:6, y=rep(0:1, length=6))
R> t(sapply(split(by.df, do.call("paste", c(by.df[, 1:2], sep = ":"))),
R+ function(x) coe
