Run every file in a folder

Question

Can I write one R script to open and run every R file in a folder?

I know how to check for the presence of a file in a folder, how to read every file in a folder as a text connection and how to read every data file in a folder.

However, I want to execute every R script in a folder one at a time, ideally using a single R script and the default R gui installed on a Windows desktop during installation.

I suspect I might need to run R from the command line instead and write some sort of batch file to do this. I have rarely run R from the command line and never written a batch file for R.

Here are some example R scripts all stored in a folder named run_all_these:

The file run.one.r contains:

a <- 10
b <- 20
c <- a+b
c

The file run.two.r contains:

a <- 10
b <- 20
c <- a-b
c

The file run.three.r contains:

a <- 10
b <- 20
c <- a*b
c

The file run.four.r contains:

a <- 10
b <- 20
c <- a/b
c

I found virtually nothing on this topic using Google. Although, I did find a little on batch files here:

http://cran.r-project.org/bin/windows/base/rw-FAQ.html

My actually R scripts will each create their own output files when run. So, I am mostly concerned with running the R scripts right now. Although the next step would be to open each R script, change a from 10 to 100 and run them again. Perhaps that should be a follow-up post.

Thank you for any suggestions.

EDIT Nov 20, 2013:

After discussion with Ricardo Saporta below I changed the four input files to:

File run.one.r:

a <- 10
b <- 20
c <- a+b
print(c)

File run.two.r:

a <- 10
b <- 20
c <- a-b
print(c)

File run.three.r:

a <- 10
b <- 20
c <- a*b
print(c)

File run.four.r:

a <- 10
b <- 20
c <- a/b
print(c)

Answer 1

I have the following function in my utils file:

## finds all .R files within a folder and soruces them
sourceEntireFolder <- function(folderName, verbose=FALSE, showWarnings=TRUE) { 
  files <- list.files(folderName, full.names=TRUE)

  # Grab only R files
  files <- files[ grepl("\\.[rR]$", files) ]

  if (!length(files) && showWarnings)
    warning("No R files in ", folderName)

  for (f in files) {
    if (verbose)
      cat("sourcing: ", f, "\n")
    ## TODO:  add caught whether error or not and return that
    try(source(f, local=FALSE, echo=FALSE), silent=!verbose)
  }
  return(invisible(NULL))
}

Answer 2

sapply( list.files(run_all_these, full.names=TRUE), source )

You would need to make sure that run_all_these was a valid Windows directory specification.

Answer 3

If you don't have subfolders:

library(tidyverse)

list.files("name_folder", full.names = TRUE) %>% walk(source)