Displaying 3 results from an estimated 3 matches for "diaga".
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diag
2015 May 05
3
Why is the diag function so slow (for extraction)?
Looks like the c(x)[...] bit used to be as.matrix(x)[...]. Not sure
why the change was made many years ago, but this was before names were
handled explicitly. It would definitely be better to not force the
duplicate, at least in the case where we are sure c() and [ would not
dispatch.
Best,
luke
On Mon, 4 May 2015, peter dalgaard wrote:
>
>> On 04 May 2015, at 19:59 , franknarf
2015 May 07
0
Why is the diag function so slow (for extraction)?
...1L && nargs() == 1L) {
n <- as.integer(x)
x <- 1
}
else n <- length(x)
if (!missing(nrow))
n <- nrow
if (missing(ncol))
ncol <- n
}
nc <- 10
set.seed(1)
m <- matrix(sample(letters,nc^2,replace=TRUE), ncol = nc)
runoff <- microbenchmark(
diaga = diag(m),
diagb = diag2(m)
)
Regards,
Steve Bronder
Website: stevebronder.com
Phone: 412-719-1282
Email: sbronder at stevebronder.com
On Tue, May 5, 2015 at 9:46 AM, <luke-tierney at uiowa.edu> wrote:
> Looks like the c(x)[...] bit used to be as.matrix(x)[...]. Not sure
> why th...
2013 Oct 11
3
matrix values linked to vector index
Hi,
In the example you showed:
m1<- matrix(0,length(vec),max(vec))
1*!upper.tri(m1)
#or
?m1[!upper.tri(m1)] <-? rep(rep(1,length(vec)),vec)
#But, in a case like below, perhaps:
vec1<- c(3,4,5)
?m2<- matrix(0,length(vec1),max(vec1))
?indx <- cbind(rep(seq_along(vec1),vec1),unlist(tapply(vec1,list(vec1),FUN=seq),use.names=FALSE))
m2[indx]<- 1
?m2
#???? [,1] [,2] [,3] [,4] [,5]