[R] Subsetting Data

[David Winsemius]

On Apr 28, 2011, at 3:13 PM, Abraham Mathew wrote:

> I'm using the subset() function in R.
>
> dat <- data.frame(one=c(6,7,8,9,10), Number=c(5,15,13,1,13))
>
> subset(dat, Number >= 10)
>
> However, I want to find the number of all rows who meet the Number>=10
> condition.
>
> I've done this in the past with something like colSums or rowSums or  
> another
> similar function.
> But I don't remember how to get the number of elements which meet that
> condition.
>
> function(subset(dat, Number >= 10))   #function is what i'm asking  
> about

Daily's answer would work but if you wanted a direct answer to your  
question then try nrow or NROW:

 > nrow(subset(dat, Number >= 10))
[1] 3

 > NROW(subset(dat, Number >= 10))
[1] 3

There is a difference and I am under the impression that NROW is safer  
in some way.


>
> In the above example, I'd run get 3 because there are 3 Number values
> greater than 10.


-- 
David Winsemius, MD
West Hartford, CT