Message-ID: <28D72DF7-F4C5-4C21-A815-AFBAA2186FA5@comcast.net>
Date: 2010-12-30T00:44:17Z
From: David Winsemius
Subject: access a column of a dataframe without qualifying the name of the column
In-Reply-To: <4D1B87CD020000CB0007CC43@medicine.umaryland.edu>
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)
>
> Confidentiality Statement:
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David Winsemius, MD
West Hartford, CT