[R] Odp: A matrix with mixed character and numerical columns

Petr PIKAL petr.pikal at precheza.cz
Thu May 31 13:57:18 CEST 2007

r-help-bounces at stat.math.ethz.ch napsal dne 31.05.2007 12:48:11:

> Is it possible to have one?
> I have a data.frame with two character columns and 6 numerical columns.
> I converted to a matrix as I needed to use the col() and row()
> functions.
> However, if I convert the data.frame to a matrix, using as.matrix, the
> numerical columns get converted to characters, and that messes up some
> of the calculations.
> Do I really have to split it up into two matrices, one character and the
> other numerical, just so I can use the col() and row() functions?  Are
> there equivalent functions for data.frames?

AFAIK I do not remember equivalent functions for data frame. If you just 
want column or row index you can use

1:dim(DF)[1] or 1:dim(DF)[2] for rows and columns

if you want repeat these indexes row or columnwise use

rrr<-rep(1:dim(DF)[1], dim(DF)[2])
matrix(rrr,dim(DF)[1], dim(DF)[2])

rrr<-rep(1:dim(DF)[2], dim(DF)[1])
matrix(rrr,dim(DF)[1], dim(DF)[2], byrow=T)


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