CODEWITHSUNDEEP
rloops
sacvf
sacvf

Reputation: 2533

How to loop to read one file after another in R?

My files are systemically named and all in the same folder. So I want to take advantage and write a function to read them one by one instead of doing this manually for each one.

The names are stored in this text file:

DF <- read.table(text="       site                column row
1          abs   1259 463
2         adm   1253 460
3        afrm   1258 463", header=T)

I want to write a function to go row by row and do this:

You can see for instance if we apply for the first row:

cor$site is abs so:

   file1=read.table("C:\\Data\\abs.txt",sep = "\t")

cor$column is 1259

cor$row is 463

So 

 wf= read.table("C:\\Users\\measurement_ 1259_463.txt", sep =' ' , header =TRUE)

Now I do any calculations with file1 and wf.........

And then go to the second row and so on.

Upvotes: 1

Views: 2133

Answers (1)

Backlin
Backlin

Reputation: 14872

Create a character vector with the file names you want to read and follow the instructions in consolidating data frames in R or reading multiple csv files in R.

files <- data.frame(
    site = paste("C:\\Data\\", DF$site, ".txt", sep=""),
    measurement = paste("C:\\Users\\measurement_", DF$column, "_",
                        DF$row, ".txt", sep=""),
    stringsAsFactors = FALSE)

results <- Map(function(s, m){
    file1 <- read.table(s, sep="\t")
    wt <- read.table(m, sep=' ', header=TRUE)
    # Do stuff
    return(result)
}, files$site, files$measurement)

# Alternatively
results <- vector("list", nrow(files))
for(i in 1:nrow(files)){
    file1 <- read.table(files$site[i], sep="\t")
    wt <- read.table(files$measurment[i], sep=' ', header=TRUE)
    # Do stuff
    results[[i]] <- # result
}

Upvotes: 2

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