[R] gsub issue in R 2.11.1, but not present in 2.9.2

[Uwe Ligges]

On 29.06.2010 12:47, Jason Rupert wrote:
> Previously in R 2.9.2 I used the following to convert from an improperly formatted NA string into one that is a bit more consistent.
>
>
> gsub("N\A", "NA", "N\A", fixed=TRUE)
>
> This worked in R 2.9.2, but now in R 2.11.1 it doesn't seem to work an throws the following error.
> Error: '\A' is an unrecognized escape in character string starting "N\A"
>
> I guess my questions are the following:
> (1) Is this expected behavior?
> (2) If it is expected behavior, what is the proper way to replace "N\A" with "NA" and "N\\A" with "NA"?


If your original text "thestring" contains "N\A", then the R 
representation is "N\\A", and hence

gsub("N\\A", "NA", thestring)

If you want to try explicitly, you need to write

gsub("N\\A", "NA", "N\\A")

If you original text contains two backslashes, both have to be escaped as in

gsub("N\\\\A", "NA", thestring)

Uwe Ligges


> Thank you again for all the help and insight.
>
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