How to Escape a Backslash in R

How to escape a backslash in R?

I found a solution that works

str = gsub("([\\])","", str)

How to escape backslashes in R string

[...] If I want to get a string containing 5 \ ,should i write 10 \ [...]

Yes, you should. To write a single \ in a string, you write it as "\\".

This is because the \ is a special character, reserved to escape the character that follows it. (Perhaps you recognize \n as newline.) It's also useful if you want to write a string containing a single ". You write it as "\"".

The reason why \\\str is invalid, is because it's interpreted as \\ (which corresponds to a single \) followed by \s, which is not valid, since "escaped s" has no meaning.

Escaping backslash (\) in string or paths in R

From R 4.0.0 you can use r"(...)" to write a path as raw string constant, which avoids the need for escaping:

r"(E:\RStuff\test.r)"
# [1] "E:\\RStuff\\test.r"

There is a new syntax for specifying raw character constants similar to the one used in C++: r"(...)" with ... any character sequence not containing the sequence )". This makes it easier to write strings that contain backslashes or both single and double quotes. For more details see ?Quotes.

Backslash symbol \ in R environment within the string block

In standard R strings the backslash is the escape symbol and hence it also needs to be escaped itself. So you need "\\alpha" to denote the string \alpha. However, wehn you use \Sexpr{} you need to escape twice, once for reading and once for writing. Thus, you need "\\\\alpha" in that case.

If you write German umlaut characters it becomes even worse because the " also has to be escaped, e.g., sch\\\\\"on" to write schön in LaTeX. But if you don't use this very often, it's not worth trying to remeber it. Instead apply the strategy from fortunes::fortune(365):

When in doubt, keep adding slashes until it works.

-- Joran Elias (on how to escape a backslash in R)

   Stackoverflow (March 2015)

substitute single backslash in R

When you need to use a backslash in the string in R, you need to put double backslash. Also, when you use gsub("\\", "/", str), the first argument is parsed as a regex, and it is not valid as it only contains a single literal backslash that must escape something. In fact, you need to make gsub treat it as a plain text with fixed=TRUE.

However, you might want to use normalizePath, see this SO thread.

Escaping a backslash with a backslash in R produces 2 backslashes in a string, not 1

may be the difference here between print and cat. So if you have the following string

usr <- "domain\\username"

and we go print(usr) we get

#[1] "domain\\username"

yet calling cat(usr) we get

#domain\username

which is what you're expecting correct? cat will actually evaluate the escapes, while print will just return the exact form of the object. You can test if your escapes are behaving as you think they should by using cat.

Check out the section on cat vs print here for a bit of info on it : R Inferno

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