[R] tapply with cbinded x

[Stefan Uhmann]

Dear List,

why does this not work?

df <- data.frame(var1 = c(3,2,1), var2 = c(6,5,4), var3 = c(9,8,7),
	fac = c('A', 'A', 'B'))
tapply(cbind(df$var1, df$var2, df$var3), df$fac, mean)

Thank you,
Stefan