[R] Prefix for colnames

[Peter Dalgaard]

jhainm at fas.harvard.edu writes:

> Hi,
> 
> I would like to add a prefix to colnames in a matrix but I can't get the prefix
> option in colnames to work. What am I doing wrong?
> 
> > X<-matrix(NA,3,4)
> > colnames(X)<-c("test","test","test","test")
> > colnames(X)<-colnames(X,prefix="PREFIX.")
> > X
>      test test test test
> [1,]   NA   NA   NA   NA
> [2,]   NA   NA   NA   NA
> [3,]   NA   NA   NA   NA
> 
> ?? I also tried with do.NULL set to FALSE but it still does not work.
> 
> Thank you very much for your help!

Well

> colnames
function (x, do.NULL = TRUE, prefix = "col")
{
    dn <- dimnames(x)
    if (!is.null(dn[[2]]))
        dn[[2]]
    else {
        if (do.NULL)
            NULL
        else paste(prefix, seq(length = NCOL(x)), sep = "")
    }
}

So if x has colnames that's what you get, irrespective of "prefix".

-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
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