[R] Can't get sample function from "An Introduction to R" to work

Marc Schwartz (via MN) mschwartz at mn.rr.com
Fri Jul 15 23:06:42 CEST 2005

On Fri, 2005-07-15 at 15:40 -0500, David Groos wrote:
> I'm trying to figure out R, a piece at a time, hours at a time...  I 
> was trying to copy the sample function in, "An Introduction to R"  (for 
> version 2.1.0) by W. N. Venables, D. M. Smith, page 42.  Section 10.1 
> "Simple examples" provides a sample function which I tried to duplicate 
> (I'm using Mac OS X 10.3.9, and "R for Mac OS X Aqua GUI v1.11).  The 
> following is what I typed and the last line is R's response when I hit 
> the return key after the penultimate line.  I've re-checked and 
> re-typed the code many times to no avail.  I wasn't able to find this 
> issue using search options, either.  Any help is GREATLY appreciated!
>  > twosam<-function(y1, y2) {
> + n1<-length(y1);n2 <-length(y2)
> + yb1<-mean(y1); yb2<-mean(y2)
> + s1<-var(y1);s2<-var(y2)
> + s<-((n1-1)*s1 + (n2-1)*s2)/(n1+n2-2)
> + tst<-(yb1-yb2)/sqrt(s*(1/n1+1/n2))
> Error: syntax error
> David

The code as you have above (without the "+" on each line) works for me
both in ESS and in the R console under Linux. There should be another
"+" on the next line, in anticipation of the remaining two lines:


Try to copy and paste the following into the console as is:

twosam<-function(y1, y2) {
 n1 <- length(y1);n2 <- length(y2)
 yb1 <- mean(y1); yb2 <- mean(y2)
 s1 <- var(y1);s2 <- var(y2)
 s <- ((n1-1)*s1 + (n2-1)*s2)/(n1+n2-2)
 tst <- (yb1-yb2)/sqrt(s*(1/n1+1/n2))

and see what happens. You should be left at a:


on a new line again.

It is possible that there is a bug in the Aqua GUI, but not using a Mac,
I cannot replicate it.

You might want to consider subscribing and posting to the R-SIG-Mac
e-mail list, which is focused on Mac users of R. More information is



Marc Schwartz

P.S. Greetings from Eden Prairie

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