[R] Calculating group means using self-written function
Lauri Nikkinen
lauri.nikkinen at iki.fi
Tue Oct 2 10:44:20 CEST 2007
Hi R-users,
Suppose I have a following data set.
y1 <- rnorm(20) + 6.8
y2 <- rnorm(20) + (1:20*1.7 + 1)
y3 <- rnorm(20) + (1:20*6.7 + 3.7)
y <- c(y1,y2,y3)
var1 <- rep(1:5,12)
z <- rep(1:6,10)
f <- gl(3,20, labels=paste("lev", 1:3, sep=""))
d <- data.frame(var1=var1, z=z,y=y, f=f)
Using following code I can calculate group means
library(doBy)
summaryBy(y ~ f + var1, data=d, FUN=mean)
How do I have to modify the FUN argument if I want to calculate mean
using unique values
for instance
fun <- function(x, y) sum(x)/length(unique(y))
summaryBy(y ~ f + var1, data=d, FUN=fun(y, z)
Error in get(x, envir, mode, inherits) : variable "currFUN" of mode
"function" was not found
Best regards
LN
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