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

[Ralikwen]

This is what I was looking for.
Using mode instead of as.numeric is a great idea.
Many thanks.
Balázs



jholtman wrote:
> 
> 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.
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
> 
> 
> 
> -- 
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
> 
> What is the problem that you are trying to solve?
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 
> 

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