Re: [R] loop? apply? I want to repeat a task through 208 itterations.

From: anna freni sterrantino <annafreni_at_yahoo.it>
Date: Fri, 04 Apr 2008 21:31:53 +0000 (GMT)


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

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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Received on Fri 04 Apr 2008 - 21:35:15 GMT

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