[R] Counting two factors at the same time

[David Winsemius]

On Jan 22, 2010, at 1:58 PM, Fabrice DELENTE wrote:

>> Try this;
>>
>>> f <- c( 'A', 'B', 'A', 'C', 'B', 'D', 'B')
>>> n <- c('1', '2', '2', '3', '2', '2', '3')
>>> table(paste(f, n))
>
> Thanks for the incredibly fast answer! I'll give this a shot!

Here's another R-way:

 > lets<-factor(c( 'A', 'B', 'A', 'C', 'B', 'D', 'B'))
# you did say they were factors, right?
 > nums <- factor(c('1', '2', '2', '3', '2', '2', '3'))
 > lets=="B"
[1] FALSE  TRUE FALSE FALSE  TRUE FALSE  TRUE
 > sum(lets=="B" & nums=="2")
[1] 2
>
-- 

David Winsemius, MD
Heritage Laboratories
West Hartford, CT