How to perform arithmetic across rows
Hi Nick, Take a look at ?cbind and ?"[" Here is some (untested) code that is how I might go about it. It takes advantage of the fact that a single value will be recycled to equal the necessary length. Then I just assign over the NA in row 24. myframe <- cbind(myframe, New = NA) myframe[24, "New"] <- with(myframe, A[1] - A[24]) New will be an all NA column except for row 24. Cheers, Josh
On Thu, Oct 28, 2010 at 11:47 AM, Nick Ackerman <nick.ackerman at pgn.com> wrote:
Hi All, I have a data frame (myframe) with variables (columns) A,B,C and 100 records (rows) for each. Column A is numeric. I would like to append a column to myframe that subtracts the value in row 24 of A from row 1 of A. In this procedure the first 23 rows of the new column will necessarily be blank (NA). Can anyone provide guidance for me here? Thanks in advance for your time. Nick -- View this message in context: http://r.789695.n4.nabble.com/How-to-perform-arithmetic-across-rows-tp3017905p3017905.html Sent from the R help mailing list archive at Nabble.com.
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Joshua Wiley Ph.D. Student, Health Psychology University of California, Los Angeles http://www.joshuawiley.com/