How do I strip dollar signs ($) from data/ escape special characters in R?

问题

I've been using gsub("toreplace","replacement", myvector) to clean out data in R. While this works for commas and the like, removing "$" has no effect. So if I do gsub("$","",myvector) all the dollar signs remain in place.

I think this is because $ is a special character in R. I tried escaping it "\$" but that yields the same result (no effect). And I couldn't find a resource on escaping special characters in R.

Obviously I should do this in preprocessing. But I was wondering if anyone out there knew how to either a) escape special characters in R b) get rid of pesky $ in R directly. For science.

回答1:

You have to escape it twice, first for R, second for the regex.

gsub('\\$', '', c("a$a", "bb$"))
[1] "aa" "bb"

See ?Quotes for details on quoting and escaping.

回答2:

Use fixed = TRUE:

gsub('$', '', c("a$a", "bb$"), fixed = TRUE)

Then you don't need to worry about any special characters. In stringr, this is implemented a little differently:

library(stringr)
str_replace_all(c("$100","ta$ty"), fixed("$"), "")

Thanks to DiggyF and James for the examples!

回答3:

Escaping characters can be a pain some times, but just putting it in square brackets (make it a character class) helps with this:

> gsub("[$]","",c("$100","ta$ty"))
[1] "100"  "taty"

来源：https://stackoverflow.com/questions/6639713/how-do-i-strip-dollar-signs-from-data-escape-special-characters-in-r