find a file using a pattern in a list of directories in r

To find a file using a pattern in a list of directories in R, you can use a combination of regular expressions, loops, and pattern matching functions. Here's an example code that searches for a file that matches a pattern in a list of directories:

main.r
# define the pattern to search for
pattern <- "example_file_.*\\.txt"

# define the list of directories to search in
dir_list <- c("dir1", "dir2", "dir3")

# loop over each directory in the list
for (dir in dir_list) {

  # get a list of all files in the directory
  file_list <- list.files(path = dir, full.names = TRUE)

  # find the files that match the pattern
  matching_files <- grep(pattern, file_list, value=TRUE)

  # print the matching files
  if (length(matching_files) > 0) {
    cat(paste("Found file(s) in directory", dir, ":\n"))
    print(matching_files)
  } else {
    cat(paste("No matching file found in directory", dir, "\n"))
  }

}
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In the code above, we define the pattern to search for as a regular expression that matches file names starting with "example_file_" and ending with ".txt". We also define a list of directories to search in. We then loop over each directory in the list, get a list of all files in the directory using the list.files() function, and use the grep() function with the value=TRUE argument to find the files that match the pattern. Finally, we print the matching files if any are found.