calculations with vectors of unequal length
See ?merge. df.1 <- data.frame(year=factor(rep(1:3,3)), level=rep(letters[1:3],3), number=c(11:19)) df.2 <- data.frame(year=factor(c(1:5)), number=c(21:25)) df.3 <- merge(df.1, df.2, by = "year") df.3$new <- with(df.3, number.x + number.y) Jeremy
On Wednesday, April 27, 2011 7:30:13 AM UTC-4, E Hofstadler wrote:
Hi there, this is probably simple but I can't seem to figure it out by myself... I have two dataframes (df.1 and df.2): df.1 <- data.frame(year=factor(rep(1:3,3)), level=rep(letters[1:3],3), number=c(11:19)) df.2 <- data.frame(year=factor(c(1:5)), number=c(21:25)) I would like to create a new variable df.1$new, which is supposed to be the sum of each element of df.1$number and those elements of df.2$number, where df.2$year equals df.1$year. What would be the most efficient way of doing this? Regards, EH
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