R help - Dec 2013 - How to plug in characters as object names in a formula (recast from package reshape2 specifically)

Hi everyone,

This may be very simple but I couldn't figure it out. I have this function

rsm.lm<-function(data,xvar='xCmin',yvar='yCmin') {

 #some calculation......

 recast(df, xvar~yvar, id.var=1:2, measure.var=3)
 #some other operations
}

df is a dataframe defined internally within the function with two id
variables (xCmin and yCmin) and a measure variable. recast doesn't work and
keep saying "Casting formula contains variables not found in molten data:
xvar, yvar......"

I tried

as.name(xvar)~as.name(yvar)
get(xvar)~get(yvar)
cat(xvar)~cat(yvar)
eval(cat(xvar))~eval(cat(yval))

But none of these works. It only works when I explicitly specify the
formula as

recast(df, xCmin~yCmin, id.var=1:2, measure.var=3)

Is there a workaround this issue? Thanks.

Jun

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Try this (untested code):

recast(df, formula(paste(xvar, "~", yvar)), id.var=1:2, measure.var=3)

Jean


On Mon, Dec 16, 2013 at 9:11 AM, Jun Shen <jun.shen.ut@gmail.com> wrote:
> Hi everyone,
>
> This may be very simple but I couldn't figure it out. I have this
function
>
> rsm.lm<-function(data,xvar='xCmin',yvar='yCmin') {
>
>  #some calculation......
>
>  recast(df, xvar~yvar, id.var=1:2, measure.var=3)
>  #some other operations
> }
>
> df is a dataframe defined internally within the function with two id
> variables (xCmin and yCmin) and a measure variable. recast doesn't work
and
> keep saying "Casting formula contains variables not found in molten
data:
> xvar, yvar......"
>
> I tried
>
> as.name(xvar)~as.name(yvar)
> get(xvar)~get(yvar)
> cat(xvar)~cat(yvar)
> eval(cat(xvar))~eval(cat(yval))
>
> But none of these works. It only works when I explicitly specify the
> formula as
>
> recast(df, xCmin~yCmin, id.var=1:2, measure.var=3)
>
> Is there a workaround this issue? Thanks.
>
> Jun
>
>         [[alternative HTML version deleted]]
>
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