Replace single backslash in R

Question

I have a string that looks like:

str<-"a\f\r" 

I'm trying to remove the backslashes but nothing works:

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

...basically all the variations you can imagine. I have even tried the string_replace_all function. ANY HELP??

I'm using R version 3.1.1; Mac OSX 10.7; the dput for a single string in my vector of strings gives:

dput(line) "ud83d\ude21\ud83d\udd2b" 

I imported the file using readLines from a standard .txt file. The content of the file looks something like: got an engineer booked for this afternoon \ud83d\udc4d all now hopefully sorted\ud83d\ude0a I m going to go insane ud83d\ude21\ud83d\udd2b in utf8towcs …

Thanks.

Answer 1

One quite universal solution is

gsub("\\\\", "", str) 

Thanks to the comment above.

Answer 2

When inputting backslashes from the keyboard, always escape them.

str <-"this\\is\\my\\string"    # note doubled backslashes -> 'this\is\my\string' gsub("\\", "", str, fixed=TRUE) # ditto  str2 <- "a\\f\\r"               # ditto -> 'a\f\r' gsub("\\", "", str2, fixed=TRUE)# ditto 

Note that if you do

str <- "a\f\r" 

then str contains no backslashes. It consists of the 3 characters a, \f (which is not normally printable, except as \f, and \r (same).

And just to head off a possible question. If your data was read from a file, the file doesn't have to have doubled backslashes. For example, if you have a file test.txt containing

a\b\c\d\e\f 

and you do

str <- readLines("test.txt") 

then str will contain the string a\b\c\d\e\f as you'd expect: 6 letters separated by 5 single backslashes. But you still have to type doubled backslashes if you want to work with it.

str <- gsub("\\", "", str, fixed=TRUE)  # now contains abcdef 

---

From the dput, it looks like what you've got there is UTF-16 encoded text, which probably came from a Windows machine. According to

• https://en.wikipedia.org/wiki/Unicode#Character_General_Category
• https://en.wikipedia.org/wiki/UTF-16

it encodes glyphs in the Supplementary Multilingual Plane, which is pretty obscure. I'll guess that you need to supply the argument encoding="UTF-16" to readLines when you read in the file.