问题
I have a matrix that contains the string "Energy per �m". Before the 'm' is a diamond shaped symbol with a question mark in it - I don't know what it is.
I have tried to get rid of it by using this on the column of the matrix:
a=gsub('Energy per �m','',a)
[and using copy/paste for the first term of gsub], but it does not work.[unexpected symbol in "a=rep(5,Energy per"]. When I try to extract something from the original matrix with grepl I get:
46: In grepl("ref. value", raw$parameter) :
input string 15318 is invalid in this locale
How can I get rid of all this sort of signs? I would like to have only 0-9, A-Z, a-z, / and '. The rest can be zapped.
回答1:
There is probably a better way to do this than with regex (e.g. by changing the Encoding).
But here is your regex solution:
gsub("[^0-9A-Za-z///' ]", "", a)
[1] "Energy per m"
But, as pointed out by @JoshuaUlrich, you're better off to use:
gsub("[^[:alnum:]///' ]", "", x)
[1] "Energy per m"
来源：https://stackoverflow.com/questions/11970891/remove-special-characters-from-data-frame