Coefficient of Variation, NA, Aggregate

HI,

Your example dataset is in unreadable format.  You could use dput().
set.seed(5)
 mat1<-matrix(sample(c(1:9,NA),20,replace=TRUE),ncol=5)
 rowleyi<-data.frame(mat1)
  co.var<-function(x) 100*(sd(x,na.rm=TRUE)/mean(x,na.rm=TRUE))
 rowleyi<-data.frame(subspecies=rep(LETTERS[1:2],2),rowleyi)


with(rowleyi,aggregate(cbind(X1,X2,X3,X4,X5),by=list(subspecies),function(x) co.var(x)))
  Group.1       X1        X2       X3       X4       X5
1       A       NA 70.710678       NA 20.20305 28.28427
2       B 56.56854  8.318903 60.60915 47.14045  0.00000


With your aggregate()
aggregate(.~subspecies,data=rowleyi,co.var)
#  subspecies       X1       X2       X3       X4 X5
#1          B 56.56854 8.318903 60.60915 47.14045  0

A.K.




----- Original Message -----
From: Amanda Jones <akjones82 at gmail.com>
To: r-help at r-project.org
Cc:
Sent: Monday, November 19, 2012 4:01 PM
Subject: [R] Coefficient of Variation, NA, Aggregate

Hello helpers,

I have a two part issue. FIRSTLY, I am attempting to write a function
for coefficient of variation, using

co.var <- function(rowleyi) ( 100*sd(rowleyi)/mean(rowleyi) )  #where rowleyi is my data set, which has multiple columns and rows of data.

This is not working because some of my columns have NAs. When I try to use

co.var(rowleyi$TL, na.rm=TRUE)  #where TL is one of my column names, it gives me an error message:

Error in co.var(rowleyi$TL, na.rm = TRUE) :
  unused argument(s) (na.rm = TRUE)

I do not know what this means. How can I get this function to work?
SECONDLY, how can I then get that function to work within an
aggragate? Do I still use

aggregate(. ~ subspecies, data = rowleyi, CV, na.rm=TRUE) #where subspecies is the header for rows? This has worked for mean, std.error, sd, etc.

Thank you!
Amanda Jones