Calculating group means using self-written function

Hi

lauri.nikkinen at gmail.com napsal dne 02.10.2007 13:19:09:
Thanks Petr,

Yes, your code seems to work. But when I try to reproduce it with my
original data set

fun <- function(x, y) sum(x)/length(unique(y))
aggregate(vsid$lev, list(vsid$month, vsid$yeari), fun, 
vsid$lev=vsid$date)

Shall be

aggregate(vsid$lev, list(vsid$month, vsid$yeari), fun, y=vsid$date)
From help page
## S3 method for class 'data.frame':
aggregate(x, by, FUN, ...)

...
further arguments passed to or used by methods.

Your function has 2 arguments one is x which is assigned vsid$lev and the 
other is y which you want to assign vsid$date. You can imagine that 
aggregate splits your "x" according to the levels mentioned in "by" and 
applies to each split a function "fun" together with any other argument, 
in your case "y". So you need to provide a correct name to your function 
otherwise it does not know what to do.

Regards
Petr
I get

Error: syntax error, unexpected EQ_ASSIGN, expecting ',' in
"aggregate(vsid$lev, list(vsid$month, vsid$year), fun, vsid$lev="

Can you intepret what is wrong? vsid$date is

$ date       :Class 'Date'  num [1:637] 13695 13695 13695 13695 13695 
...
Cheers,
Lauri

2007/10/2, Petr PIKAL <petr.pikal at precheza.cz>:
Hi

r-help-bounces at r-project.org napsal dne 02.10.2007 10:44:20:

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
Not sure how to do it in doBy but using aggregate

aggregate(d$y, list(d$var1,d$f), fun, y=z)

probably do what you want

Regards
Petr

Best regards
LN

______________________________________________
R-help at 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.

Calculating group means using self-written function

Thread (7 messages)