[R] Odp: convert factor dataframe into numeric matrix

Petr PIKAL petr.pikal at precheza.cz
Wed Oct 24 15:09:19 CEST 2007


r-help-bounces at r-project.org napsal dne 24.10.2007 14:51:10:

> Bear me if this is a naive question.
> I have a dataframe, all lists inside it are factors. When I use 
> as.matrix(df) to convert, I get a character matrix while my intention is 
> get numeric matrix. I can make the convertion  iteratively by each list 
> I do think there is some more elegant way of doing this.
> please let me know if I missed somthing there.

You missed to provide several information, mainly some example.

1.      How did you get nonumeric data frame? If it is by transfer from 
Excel or something like that, you definitelly shall look at raw data as 
there is some mismatch. R tries to keep numeric as numeric but converts 
character to factor.
2.      Are the values numeric? I presume that yes. So you can use e.g. 

 sapply(dat, function(x) as.numeric(as.character(x)))


>  Thanks in advance.
> Sun
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