[R] Q: changing the class of an object

Uwe Ligges ligges at statistik.uni-dortmund.de
Thu May 26 18:55:18 CEST 2005

Dave Evens wrote:

> Dear All,
> I have a list of dataframes, each cell in every

what is a cell?

> dataframe (after I have cleaned up the dataframes) is
> either real or NA  but have class character (I think).
> I would like to know how to change the class of every
> cell without using a for-loop. I currently have this
> dataframes <- sapply(1: no.of.subs, function(k)
> apply(dataframes[[k]], 2, function(x) {         
> if(class(x)=="character") x <- as(x, "numeric"); x }))
> but this neither changes the cells to numeric nor
> keeps the dataframes in a list.
> It creates one dataframe with number of rows=(no of
> rows in a dataframe*no of colums) and number of
> columns = no.of.subs
> Can someone please help? Thanks in advance for any
> help.

A simple way is

   data.frame(sapply(X, as.numeric))

but I guess the real problem is some steps before. You should take a 
look why you got character vectors in your data.frame rather than 
numeric ones.

Uwe Ligges

> Dave
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