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

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