[R] Extracting arithmetic mean for specific values from multiple .txt-files

[Rui Barradas]

Hello,

Ok, I think that there were two problems.
One, gsub substitutes all (g - global) occurrences of the search 
pattern, so both periods were removed.
The other, it would allways consider column 8 as character, but when 
there are no values with two periods it's read in with class numeric.
Both are now corrected.



fun <- function(x, skip = 14){
     dat <- read.table(x, skip=skip, stringsAsFactors = FALSE)
     if(is.character(dat[, 8])){
         len <- sapply(strsplit(dat[, 8], "\\."), length)
         dat[len == 3 , 8] <- sub("\\.", "", dat[len == 3 , 8])
         dat[, 8] <- as.numeric(dat[, 8])
     }
     mean(dat[, 8])
}

sapply(list.files(pattern="XYZ.*\\.txt"), fun)


Rui Barradas

Em 10-07-2012 09:35, vimmster escreveu:
> Dear Mr. Holtman,
>
> but I cannot leave out the value and cannot change the values to 1200.995
> manually (for each test subject with a reaction time > 1000 ms), because the
> first your lead to incomplete data and the latter would be too
> time-consuming.
>
> Dear Rui,
>
> here I have three files, which have exactly the same content as
> "XYZ_34.txt", EXCEPT that the file "XYZ_50.txt" doesn't have a period in the
> first value 1200.9952 IF YOU OPEN IT WITH THE EDITOR (!), maybe because I
> didn't change the structure with MS Excel. The other two files should be
> identical.
>
> http://r.789695.n4.nabble.com/file/n4635962/XYZ_2.txt XYZ_2.txt
> http://r.789695.n4.nabble.com/file/n4635962/XYZ_50.txt XYZ_50.txt
> http://r.789695.n4.nabble.com/file/n4635962/XYZ_1112.txt XYZ_1112.txt
>
> R gives me the following output:
>
>> fun <- function(x){
> +     dat <- read.table(x, skip=14)
> +     dat[ , 8] <- as.numeric(gsub("\\.", "", dat[, 8]))
> +     mean(dat[, 8])
> + }
>
>> sapply(list.files(pattern="XYZ.*\\.txt"), fun)
> XYZ_1112.txt    XYZ_2.txt   XYZ_50.txt
>      345210.4     345210.4     310112.0
>
> Your second suggestion leads to the same output:
>
>> fun <- function(x, skip = 14){
> +     dat <- read.table(x, skip=skip)
> +     dat[ , 8] <- as.numeric(gsub("\\.", "", dat[, 8]))
> +     mean(dat[, 8])
> + }
>
>> sapply(list.files(pattern="XYZ.*\\.txt"), fun)
> XYZ_1112.txt    XYZ_2.txt   XYZ_50.txt
>      345210.4     345210.4     310112.0
>
> Thank you for your replies!
>
> Kind regards
>
> --
> View this message in context: http://r.789695.n4.nabble.com/Extracting-arithmetic-mean-for-specific-values-from-multiple-txt-files-tp4635809p4635962.html
> Sent from the R help mailing list archive at Nabble.com.
>
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