Analogy for %in% for the whole columns (rather than individual values)

Hi Dimitri,

What about this:

with(a, x == y) -> a$equal
a

???? x??? y equal
1 john mary FALSE
2 mary mary? TRUE
3 mary john FALSE
4 john john? TRUE

/Fredrik

On Thu, Mar 26, 2009 at 7:48 PM, Dimitri Liakhovitski <ld7631 at gmail.com>
wrote:

Hello!

I have a matrix a with 2 variables (see below) that contain character
strings.
I need to create a 3rd variable that contains True if the value in
column x is equal to the value in column y. The code below does it.

a<-data.frame(x=c("john", "mary", "mary",
"john"),y=c("mary","mary","john","john"))
a$x<-as.character(a$x)
a$y<-as.character(a$y)
a$equal<-NA
for(i in 1:nrow(a)) {a[i,3]<-a[i,1] %in% a[i,2]}

I was wondering if one can do it faster, without doing it row-by-row
as I did it. Maybe there is a faster way to compare 2 columns?

Thank you very much!

--
Dimitri Liakhovitski
MarketTools, Inc.
Dimitri.Liakhovitski at markettools.com

--
"Life is like a trumpet - if you don't put anything into it, you don't get
anything out of it."