list files in folder matching an exact filename

Question

I have a number of files in my folder, e.g.:

• file1.txt
• file1.txt_sub
• file1.txt_sub2

I only wish R to find "file1.txt". But if I use

list.files(pattern = "file1.txt")

R will also return the other two files from my example. Any ideas how I could solve this?

Thanks!

Answer 1

Use regular expressions (see ?regex):

list.files(pattern = "^file1\\.txt$")

^ is the regular expression denoting the beginning of the string,
\\ escapes the . to make it a literal .,
$ is the regular expression denoting the end of the string.

In sum, this is the regular expression capturing exactly file1.txt and nothing else.