Help summarizing R data frame
Here are some examples with tapply, aggregate, ddply:
x <- read.table("clipboard", head=TRUE)
with(x, tapply(quantity, identifier, sum))
aggregate(x$quantity, by=list(x$identifier), sum)
aggregate(quantity ~ identifier, data = x, sum)
library(plyr)
ddply(x, .(identifier), summarise, quantity=sum(quantity))
HTH
Patrick
Am 02.12.2010 17:24, schrieb chris99:
I am trying to aggregate data in column 2 to identifiers in col 1 eg.. take this> identifier quantity 1 10 1 20 2 30 1 15 2 10 3 20 and make this> identifier quantity 1 45 2 40 3 20 Thanks in advance for your help!