On 2020-04-03 07:39 +1100, Jim Lemon wrote:
|
| Hi Rasmus,
| Very nice. The R help list is a bit like a
| quiz show where the contestants must
| balance the alacrity with which they press
| their buttons with the confidence that they
| have the correct answer. A slow motion game
| of wits in
On 2020-04-01 15:33 +1100, Jim Lemon wrote:
> Hi Nevil,
> It's a nasty piece of work, but:
Hi! How about this one:
data <- c(rep(1:4, times=3), 2, 1, 3, 2)
dimnames <- list(NULL, c("x", "y", "z", "k"))
ncol <- length(data)/4
M <- matrix(data=data, nrow=ncol, ncol=ncol, dimnames=d
Hi Rasmus,
Very nice. The R help list is a bit like a quiz show where the
contestants must balance the alacrity with which they press their
buttons with the confidence that they have the correct answer. A slow
motion game of wits in which the prizes are self-awarded.
Jim
On Fri, Apr 3, 2020 at 7:
Hi Nevil,
It's a nasty piece of work, but:
M<-matrix(c(1,2,3,4,1,2,3,4,1,2,3,4,2,1,3,2),4,4,
dimnames = list(NULL, c("x", "y", "z","k")))
M
reprow<-function(x)
return(matrix(rep(x,x[length(x)]),nrow=x[length(x)],byrow=TRUE))
toseq<-function(x) return(1:x)
j<-unlist(sapply(M[,"k"],toseq))
Mlist<-a
OK sorted - hope these postings might help someone else
Any even faster options would be appreciated still
#seq() does not work but sequence() does
print("rep and sequence")
print(system.time({
j<-NULL
MOut<-NULL
MOut<-M[rep(1:nrow(M), times = M[,4]), ]
j<-sequence(M[,4])
MOut<-cbind(M
Well,
I found a way to do it partly using rep(), and one loop that makes it 10x
or more faster however would still be good to do without the loop at all
matrix made slightly beigger (1 rows):
M<-matrix(c(1:3
), 1,3)
M<-cbind(M,sample(1:5,size = 1,replace = T))
#Print(M)
#Create mat
False premise: rep works fine
Mout2 <- cbind(M[ rep(seq.int(nrow(M)),M[,"k"]),
c("x","y","z")],unlist(lapply(M[,"k"],seq.int)))
On March 31, 2020 6:18:37 PM PDT, nevil amos wrote:
>Hi
>
>I can achieve this using two for loops but it is slow I need to do
>this on
>many matrices with tens of mil
Hi
I can achieve this using two for loops but it is slow I need to do this on
many matrices with tens of millions of rows of x,y,z and k
What is a faster method to achieve this, I cannot use rep as j changes in
each row of the new matrix
###
M<-matrix(
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