Thanks Dennis. I noticed I didn't take the "0" value into consideration and
also didn't check the unsorted vector.vec1<- c(2,4,1)
is.numeric(vec1)
#[1] TRUE
makeMat(as.integer(vec1))
makeMatrix2<- function(x){
if(is.numeric(x)){
x <- as.integer(round(x))
x}
stopifnot(is.integer(x))
m1<- matrix(0,length(x),max(x))
indx <-
cbind(rep(seq_along(x),x),seq_len(sum(x))-rep(cumsum(c(0L,x[-length(x)])),x))
m1[indx]<- 1
m1}
identical(makeMat(x1),makeMatrix2(x1))
#[1] TRUE
identical(makeMat(x2),makeMatrix2(x2))
#[1] TRUE
identical(makeMat(x3),makeMatrix2(x3))
#Error: is.integer(x) is not TRUE
makeMatrix2(x3)
# [,1] [,2]
#[1,] 1 1
#[2,] 1 0
#[3,] 1 1
identical(makeMat(4:6),makeMatrix2(4:6))
#[1] TRUE
x4 <- c("a",1,3)
identical(makeMat(x4),makeMatrix2(x4))
#Error: is.integer(x) is not TRUE
A.K.
On Friday, October 11, 2013 4:41 PM, Dennis Murphy <djmu...@gmail.com> wrote:
Attempting to follow the OP's conditions and assuming I understood
them correctly, here is one way to wrap this up into a function:
makeMat <- function(x)
{
stopifnot(is.integer(x))
nr <- length(x)
nc <- max(x)
# Initialize a matrix of zeros
m <- matrix(0, nr, nc)
# Conditionally replace with ones
for(i in seq_len(nr)) if(x[i] != 0) m[i, 1:x[i]] <- 1
m
}
## Examples:
x1 <- 1:3
x2 <- as.integer(c(2, 0, 4, 3, 1))
x3 <- c(2, 1, 2.2)
makeMat(x1)
makeMat(x2)
makeMat(x3)
makeMat(4:6)
On Fri, Oct 11, 2013 at 9:49 AM, arun <smartpink...@yahoo.com> wrote:
> 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]
> #[1,] 1 1 1 0 0
> #[2,] 1 1 1 1 0
> #[3,] 1 1 1 1 1
>
>
>
>
> A.K.
>
>
> Hi-
>
> I'd like to create a matrix of 0's and 1's where the number of
> 1's in each row defined by the value indexed in another vector, and
> where the (value-1) is back-filled by 0's.
>
> For example, given the following vector:
> vec= c(1,2,3)
>
> I'd like to produce a matrix with dimensions (length(vec), max(vec)):
>
> 1,0,0
> 1,1,0
> 1,1,1
>
> Thank you!
>
> ______________________________________________
> 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.
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and provide commented, minimal, self-contained, reproducible code.
