access a column of a dataframe without qualifying the name of the column

On Dec 29, 2010, at 7:11 PM, John Sorkin wrote:

I am trying to write a function that will access a column of a data frame
without having to qualify the name of the data frame column as long as the
name of the dataframe is passed to the function. As can be seen from the
code below, my function is not working:

Not sure what the verb "qualify" means in programming. Quoting?

df <- data.frame(x=1:10,y=11:20)
df

test <- function(column,data) {
 print(data$column)
}

test(x,df)

I am trying to model my function after the way that lm works where one
needs not qualify column names, i.e.

df <- data.frame(x=1:10,y=11:20)
test <- function(column,dat) { print(colname <-
deparse(substitute(column)))

+  dat[[colname]]
+ }

test(x,df)

[1] "x"
 [1]  1  2  3  4  5  6  7  8  9 10

--
David.

fit1<- lm(y~x,data=df)


John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)

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David Winsemius, MD
West Hartford, CT