I have a function of two arguments, (m, n) that returns a list with the
same structure as the function makefoo below.
When m=1, it returns a list of vectors, each of length n.
When m>1, it returns a list of square matrices, each of size m x m.
makefoo <- function(m, n) {
if (m==1) {
A <- sample(1:100, n)
B <- sample(1:100, n)
C <- sample(1:100, n)
}
else {
A <- B <- C <- list(rep(0, n))
for (i in seq(n)) {
A[[i]] <- matrix(sample(1:100, m^2), m, m)
B[[i]] <- matrix(sample(1:100, m^2), m, m)
C[[i]] <- matrix(sample(1:100, m^2), m, m)
}
}
result <- list(m=m, A=A, B=B, C=C)
class(result) <- "foo"
result
}
I'd like to define an as.data.frame function for class "foo" object that
applies either det() or tr() to the matrices
in the case m>1. The function below works, but I'd rather define the
argument FUN as c(det, tr) and use
something like match.arg(FUN) to determine which was supplied. Is there
some easy way to do this?
# matrix trace
tr <- function(M) sum(diag(M))
# why can't I use FUN=c(det, tr) & match.arg(FUN) below?
as.data.frame.foo <- function(x, FUN=det) {
m <- x$m
if(m==1) df <- with(x, data.frame(A, B, C))
else {
# FUN <- match.arg(FUN)
A <- unlist(lapply(x$A, FUN))
B <- unlist(lapply(x$B, FUN))
C <- unlist(lapply(x$C, FUN))
df <- data.frame(A, B, C)
colnames(df) <- paste(deparse(substitute(FUN)), c("A", "B",
"C"), sep="")
}
df
}
### Test cases ####
> foo1 <- makefoo(1, 4)
> as.data.frame(foo1)
A B C
1 38 86 49
2 67 65 2
3 41 46 82
4 59 8 78
>
> foo2 <- makefoo(2, 4)
> as.data.frame(foo2)
detA detB detC
1 -342 -5076 -2621
2 -4712 1568 -1724
3 -4491 -1892 -2768
4 2990 -5448 2974
> as.data.frame(foo2, FUN=tr)
trA trB trC
1 118 65 80
2 62 85 99
3 108 86 98
4 110 23 129
>
--
Michael Friendly Email: friendly AT yorku DOT ca
Professor, Psychology Dept.
York University Voice: 416 736-5115 x66249 Fax: 416 736-5814
4700 Keele Street Web: http://www.datavis.ca
Toronto, ONT M3J 1P3 CANADA
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
