Parameter of a function used after $ in a data frame

Use [[ instead of $.   E.g.,

f <- function(columnName) {
    d <- data.frame(x=1, y=2, z=3)
    d[[columnName]]
}
f("z") # 3
cName <- "y"
f(cName) # 2

Bill Dunlap
TIBCO Software
wdunlap tibco.com

Hi,
Can anyone please tell me how to use a argument of a function after $ sign
of a data frame.That argument is one of the column name of the data frame.

Thanks,
Madhvi

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