On Apr 28, 2011, at 3:38 PM, David Winsemius wrote:
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.
> NROW
function (x)
if (is.array(x) || is.data.frame(x)) nrow(x) else length(x)
So if you were doing something with tapply or a [,] subsetting
operation which might return a single dimensioned result you would
definitely want NROW.
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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David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
