On May 18, 2011, at 3:12 PM, John Poulsen wrote:
Hello,
I want to build a function to call up a column of a data.frame by
the names of the columns. I have column names that are sequentially
named (col1, col2, etc.). How do I change a character expression
into something that will be understood as a data.frame column. For
example:
example<-data.frame(cbind(col1=1:10, col2=21:30, col3=41:50))
call.fun<-function(t){
x<-paste("col",t, sep="") ## Change this so that it is the data,
not a character expression
# right.... don't use the "$" operator, instead use "[["
example[[x]] }
call.fun(t=2)
Within the real function, I will continue do calculations on the
column of data. My problem is that I am either getting a character
expression or NULL from my function.
Thanks for your help on what is probably a very simple question.
John
--
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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