Hello all, I have not been able to find an answer to this problem. I feel like it might be so simple though that it might not get a response.
Suppose I have a dataframe like the one I have copied below (minus the 'calib' column). I wish to create a column like calib where I am subtracting the 'Count' when 'stain' is 'none' from all other 'Count' data for every value of 'rep'. This is sort of analogous to putting a $ in front of the number that identifies a cell in a spreadsheet environment. Specifically I need some like this: mydataframe$calib <- Count - (Count when stain = none for each value rep) Any thoughts on how I might accomplish this? Thanks in advance. Sam Note: I've already calculated the calib column in gnumeric for clarity. rep Count stain calib 1 1522 none 0 1 147 syto -1375 1 544.8 sytolec -977.2 1 2432.6 sytolec 910.6 1 234.6 sytolec -1287.4 2 5699.8 none 0 2 265.6 syto -5434.2 2 329.6 sytolec -5370.2 2 383 sytolec -5316.8 2 968.8 sytolec -4731 3 2466.8 none 0 3 1303 syto -1163.8 3 1290.6 sytolec -1176.2 3 110.2 sytolec -2356.6 3 15086.8 sytolec 12620 -- ***************************************************** Sam Albers Geography Program University of Northern British Columbia 3333 University Way Prince George, British Columbia Canada, V2N 4Z9 phone: 250 960-6777 ***************************************************** [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.