Michael,
I have to agree with Don that using a factor as a loop index seems
like a risky choice. At any rate, part of the problem is that you are
referencing a nonexistant part of your dataframe. i is an index of
characters, but your rownames are 1:5, not LETTERS[1:5]. If you give
your dataframe rownames, you can then use your loop, see below.
########################
locn<-c("A", "B", "C", "D", "E")
n<-c(28, 14, 21, 52, 35)
corr.r<-c(0.40, 0.63, 0.38, 0.44, 0.35)
lab8.dat<-data.frame(locn, n, corr.r)
lab8.dat
calc.prob.t<-function(n, r)
{
df<-n-2
t<-(r-0)/(sqrt((1-r^2)/df)) # I'm assuming you mean r^2 here not r2
probt<-2*(pt(t, df, lower.tail=FALSE))
probt
}
p_unadj<-NULL # since you assign it to null anyways, there's not real
point in the other assignment
p_unadj
for ( i in lab8.dat[,1] )
p_unadj[i] <- calc.prob.t(lab8.dat[i,2], lab8.dat[i,3])
p_unadj # all NAs as you noticed
rownames(lab8.dat) <- lab8.dat$locn
for ( i in lab8.dat[,1] )
p_unadj[i] <- calc.prob.t(lab8.dat[i,2], lab8.dat[i,3])
p_unadj # now lab8.dat["A",2] etc. means something, and it works
##############################
On Tue, Mar 16, 2010 at 7:53 PM, Michael Rennie <mdren...@gmail.com> wrote:
Hi gang,
I'm perplexed- I have some code that uses for() loops that works fine in R
version 2.8 on my mac, worked fine in version 2.8 on my old windows machine,
but doesn't work in version 2.10 on windows.
The loop implements a function over a data frame (code is included below).
In Mac (running version 2.8), the results of the loop are what I expect:
p_unadj
[1] 0.034939481 0.015743706 0.089287030 0.001098538 0.039290594
But in Windows (running version 2.10.1), I get a bunch of NA's...
p_unadj
A B C D E
NA NA NA NA NA
If I had to guess, I'd say that R v. 2.10 is handling the i in lab8.dat[,1]
differently, given that it's keeping the row names in the output for
p_unadj... but why would that stop it from applying the function?
Any thoughts or suggestions are welcome.
Cheers,
Mike
Here's the code...
#build the dataset
locn<-c("A", "B", "C", "D", "E")
n<-c(28, 14, 21, 52, 35)
corr.r<-c(0.40, 0.63, 0.38, 0.44, 0.35)
lab8.dat<-data.frame(locn, n, corr.r)
lab8.dat
attach(lab8.dat)
#write the function
calc.prob.t<-function(n, r)
#given a sample size (n) and correlation coefficient (r), returns the
probability for that test
{
df<-n-2
t<-(r-0)/(sqrt((1-r2)/df))
probt<-2*(pt(t, df, lower.tail=FALSE))
probt
}
#try out the function...
calc.prob.t(lab8.dat$n[1], lab8.dat$corr.r[1])
#it works.
#write a loop to implement that function for every correlation in your
dataset...
p_unadj<-numeric(length(lab8.dat[,1]))
p_unadj<-NULL
p_unadj
#all this just built an empty vector to store the results of our loop...
for ( i in lab8.dat[,1] )
p_unadj[i]<-calc.prob.t(lab8.dat[i,2], lab8.dat[i,3])
p_unadj
#if executed on my Mac, running R v.2.8, this works (and did using 2.8 on my
old windows machine). Running v. 2.10 in Windows, I get NAs.
--
Michael D. Rennie, Ph.D.
Postdoctoral Fellow, Environmental and Life Sciences Program
Trent University
> 2140 East Bank Drive, DNA Building (2nd Floor)
Peterborough, Ontario K9J 7B8
Vox:705.755.2287 Fax:705.755.1559
www.*people.trentu.ca/michaelrennie
______________________________________________
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PLEASE do read the posting guide
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and provide commented, minimal, self-contained, reproducible code.
--
Joshua Wiley
Senior in Psychology
University of California, Riverside
http://*www.*joshuawiley.com/
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://*www.*R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
