[R] c(1:n, 1:(n-1), 1:(n-2), ... , 1)

[John McKown]

I'm not too sure this is any better:

n<-5
c<-0; # establish result as numeric
for(i in seq(n,1,-1)){ c<-c(c,seq(1,i)); str(c); }; #generate array
c<-c[2:length(c)]; #remove the leading 0

If you're a fan of recursive programming:

> mklist <- function(x) { if (x==1) return(1) else return(
c(seq(1,x),mklist(x-1)) ) ; }
> mklist(5);
 [1] 1 2 3 4 5 1 2 3 4 1 2 3 1 2 1
>

Of course, I've not done any error checking in my function definition. And,
for large values, it can nest too deeply and get

Error: evaluation nested too deeply: infinite recursion /
options(expressions=)?


On Thu, Sep 17, 2015 at 1:19 PM, Dan D <ddalthorp at usgs.gov> wrote:

> Can anyone think of a slick way to create an array that looks like c(1:n,
> 1:(n-1), 1:(n-2), ... , 1)?
>
> The following works, but it's inefficient and a little hard to follow:
> n<-5
> junk<-array(1:n,dim=c(n,n))
> junk[((lower.tri(t(junk),diag=T)))[n:1,]]
>
> Any help would be greatly appreciated!
>
> -Dan
>
>
>
> --
> View this message in context:
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> Sent from the R help mailing list archive at Nabble.com.
>
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-- 

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John McKown

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