[R] converting values of a dataframe to numeric (where possible)

[jim holtman]

Try this as a solution:

> df <- data.frame(a=letters[15:17], b=c("21","NA","23"), c=10:12, d=15:17)
> # convert to numeric
> x <- as.matrix(df)
> mode(x) <- "numeric"
Warning message:
In eval(expr, envir, enclos) : NAs introduced by coercion
> cbind(df, RTot=rowSums(x, na.rm=TRUE))
  a  b  c  d RTot
1 o 21 10 15   46
2 p NA 11 16   27
3 q 23 12 17   52
>


On Tue, Sep 2, 2008 at 5:50 PM, Ralikwen <Balazs.Klein at gmail.com> wrote:
>
> Hi,
> I am new to R.
> I have a dataframe with many columns some of which contain genuine strings
> some numerical values as strings. The dataframe is created by cast so I have
> no control over the resulting data type.
> I want to attach columns as aggregates of other columns to the dataframe.
> Here is the solution that I came up with (after a lot of struggle):
>
> castNum <- function(n) {
>    x<-as.numeric(as.character(n))
>    if (is.na(x)){
>      return(n)
>    }else{
>      return(x)
>    }
> }
> df <- data.frame(a=letters[15:17], b=c("21","NA","23"), c=10:12, d=15:17)
> cbind(df,RTot=rowSums(as.data.frame(lapply(df, function(x)
> castNum(x)))[2:4],na.rm=TRUE))
>
> This works, but is full of warnings and looks extremely ugly.
> Could you direct me how to achieve the same result in a more elegant way?
>
> Thx.
> Balázs
>
>
>
> --
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> Sent from the R help mailing list archive at Nabble.com.
>
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-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?