I have a string:
s <- "test.test AS field1, ablh.blah AS field2, faslk.lsdf AS field3"
I want to convert to:
"field1, field2, field3"
I know that the regular expression (\w+)(?:,|$) will extract the strings I want ('field1,' etc) but I can't figure out how to extract it with gsub.
## Preparation
s <- "test.test AS field1, ablh.blah AS field2, faslk.lsdf AS field3"
pat <- "(\\w+)(?:,|$)" ## Note the doubly-escaped \\w
## Use the powerful gregexpr/regmatches one-two punch
m <- gregexpr(pat, s)
paste(regmatches(s, m)[[1]], collapse=" ")
# [1] "field1, field2, field3"
With strapplyc in the gsubfn package one can do it with a particularly simple regular expression which extracts each string of word characters that follows " AS " (If the field can contain non-word characters then replace \\w with the appropriate expression, for example any char that is not a space or comma: [^ ,]):
> library(gsubfn)
> strapplyc(s, " AS (\\w+)", simplify = toString)[[1]]
[1] "field1, field2, field3"
