[R] how to loop through dataframe objects in environment

[Vikash Kumar]

Hi Stephen,

Try out lapply(). It would help you loop through all data frames and sum.

Regards,
Vikash

On Thu, Oct 16, 2014 at 1:58 AM, Stephen HK Wong <honkit at stanford.edu>
wrote:

> Dear All,
>
> I  have many 50 objects they are all dataframes. Each dataframe has many
> rows and four column. I simply want to do an addition of 3rd and 4th column
> and save the result into 5th column. Since there are many dataframes, I
> don't want to do it one by one,  is there a way to loop through all objects
> and perform the similar action ?
>
> One way I can think of is like this:
>
> for (i in 1:50){
> get(ls()[i])[,3]+get(ls()[i][,4]
> }
>
> But I don't know how to save the addition result back to 5th column of
> each dataframe.
>
>
> Many Thanks!
>
>
>
> Stephen HK Wong
>
> ______________________________________________
> 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.
>

	[[alternative HTML version deleted]]