[R] summaryBy: transformed variable on RHS of formula?

Alexander Shenkin ashenkin at ufl.edu
Mon Apr 2 17:58:43 CEST 2012


Hi Folks,

I'm trying to cut my data inside the summaryBy function.  Perhaps
formulas don't work that way?  I'd like to avoid adding another column
if possible, but if I have to, I have to.  Any ideas?

Thanks,
Allie

    require(doBy)
    df = dataframe(a <- rnorm(100), b <-rnorm(100))
    summaryBy(a ~ cut(b,c(-100,-1,1,100)), data=df) # preferred
solution, but it throws an error
                                                    # Error in
`[.data.frame`(data, , rh.var, drop = FALSE) : undefined columns selected

    df$c = cut(b,c(-100,-1,1,100))
    summaryBy(a ~ c, data=df)       # works fine



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