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

[David Winsemius]

You can add this to the list of options to be tested, although my bet would be placed on `sequence(5:1)`:

> Reduce( function(x,y){c( 1:y, x)}, 1:5)
 [1] 1 2 3 4 5 1 2 3 4 1 2 3 1 2 1


On Sep 17, 2015, at 11:40 AM, Achim Zeileis wrote:

> On Thu, 17 Sep 2015, Peter Langfelder wrote:
> 
>> Not sure if this is slicker or easier to follow than your solution,
>> but it is shorter :)
>> 
>> do.call(c, lapply(n:1, function(n1) 1:n1))
> 
> Also not sure about efficiency but somewhat shorter...
> unlist(lapply(5:1, seq))
> 
>> Peter
>> 
>> On Thu, Sep 17, 2015 at 11:19 AM, 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
>>> 
>>> 

David Winsemius
Alameda, CA, USA