Problem with loop

3 messages · Komine, R. Michael Weylandt

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Komine

Fri, Dec 2, 2011 9:15 AM #

Hi, 
I try to build a loop difficultly. 
I have in a folder called Matrices several files (.csv) called Mat2002273,
Mat2002274  to Mat2002361. 
I want to calculate for each file the mean of the column called Pixelvalues.
I try this code but as result, I have this message:  Mat2002273 not found

Thank you for your help 




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R. Michael Weylandt

Fri, Dec 2, 2011 9:55 AM #

You never create a variable called "Mat2002273" or "Mat2002361" so you
can't ask R to loop over all the values between them.

If I were you, I'd code something like this:

lf <- list.files()

# PUT IN SOME CODE TO REMOVE FILES YOU DON'T WANT TO USE

pv <- vector("numeric", length(lf))

for(i in lf) pv[i] <- mean( read.csv(lf, header = TRUE)[,"Pixelvalues"])

print(pv)

Michael

On Fri, Dec 2, 2011 at 12:15 PM, Komine <momadou at yahoo.fr> wrote:

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and provide commented, minimal, self-contained, reproducible code.

1 day later

Komine

Sat, Dec 3, 2011 10:19 AM #

Hi, 
Thank Michael for your help.
Komine

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