[R] passing function parameters into a 'with' statement to dynamically pick out columns

[Jeff Newmiller]

"With" is designed for interactive use, so you are right that it is not the answer.

You can use list indexing with column names within functions, though, like df[[scaling.column]] or df[["all"]].
---------------------------------------------------------------------------
Jeff Newmiller                        The     .....       .....  Go Live...
DCN:<jdnewmil at dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live Go...
                                      Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
/Software/Embedded Controllers)               .OO#.       .OO#.  rocks...1k
--------------------------------------------------------------------------- 
Sent from my phone. Please excuse my brevity.

David Marx <dmarx at SOUNDEXCHANGE.COM> wrote:

>Hi,
>
>I've built a function to generate plots and would like to be able pass
>in column names as a parameter. Here's a boiled down version of what I
>have right now:
>
>pmts <- data.frame(date=c(1,2,3),
>all=c(5,6,7),maj=c(4,5,6),ind=c(3,4,5))
>perc.mktshare <- function(df){  
>  range1 <- floor(min(with(df, 100*ind/all)))
>  range2 <- ceiling(max(with(df, 100*ind/all)))  
>with(df,plot(date,100*ind/all,ylim=c(range1,range2),ylab="%
>Marketshare"))
>}
>perc.mktshare(pmts)
>
>What I'd like to do is something like this:
>
>perc.mktshare <- function(df, scaling.column){  
>  range1 <- floor(min(with(df, 100*scaling.column/all)))
>  range2 <- ceiling(max(with(df, 100*scaling.column/all)))  
>with(df,plot(date,100*"scaling.column"/all,ylim=c(range1,range2),ylab="%
>Marketshare"))
>}
>perc.mktshare(pmts,"ind")
>perc.mktshare(pmts,"maj")
>
>I've tried going about this a couple of different ways but I can't make
>it work. My suspicion is that there's probably no way to do this using
>the 'with' statement and I'll have to trim the input dataframe to the
>pertinent columns first using subset or something.
>
>Thanks for your help!
>
>David
>
>______________________________________________
>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.