Dear R-helpers, I have a data frame that is similar to the one below. The row names are species and the E1, E2, E3 columns are presence/absence for a given site. I have an additional column 'origin' which has information about the species.
E1 E2 E3 origin BASA 0 0 1 N BASO 0 0 1 N BRCO 0 0 1 U CAER 0 0 0 E CAGI 0 1 0 C CEFL 0 1 1 N I want to get the sum of ALL of the sites for the factors in the column 'origin'. I have used by(merge[,2],merge$origin,sum) and tapply(merge[,2],merge$origin,sum) but this just gives me one column at a time. How can I get all of the sites summed individually and end up with the site names as rows and the factors be the columns. Thanks in advance for your help! Michael ______________________________________________ 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.