hi Stephen,
you may want to check  
?apply 


What you want is :
a<-matrix(1:120,10,20)
 a[1:8,1:2]=NA
apply(a,2, function(x) if(sum(!is.na(x)) > (length(x)-3)) shapiro.test(x) else NA )

Cheers
Anna


----- Messaggio originale -----
Da: stephen sefick <ssefick@gmail.com>
A: r-help@r-project.org
Inviato: Venerdì 4 aprile 2008, 8:44:45
Oggetto: [R] loop? apply? I want to repeat a task through 208 itterations.

structure(list(RM215alk = c(15, 13, 12, 14, NA, 13, 16, 13, 16,
#subset of data
13, 17, 13, 19, 13, 14, 14, 15, 15, 14, 16, 14, 15, 13, 14),
    NSCl = c(NA, NA, 2.9, NA, NA, NA, NA, NA, NA, NA, NA, NA,
    NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA)), .Names = c("RM215alk",
"NSCl"), class = "data.frame", row.names = c(NA, -24L))

apply(if n>=3(x.f, 2, shapiro.test)else(NULL)) #crappy code showing my
lack of knowledge on the subject

I would like to apply this to a 208 column data matrix, and this is
the first time I have tried a repetitive task in R- so please bear
with me.  the shapiro.test requires 3 to 5000 observations and there
are some columns that don't have three observation making it
unnecessary to preform a test for normality.  How do I do this?
thanks

stephen
-- 
Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods. We are mammals, and have not exhausted the
annoying little problems of being mammals.

    -K. Mullis

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