library(stringr)
x <- str_extract_all(strLine,"\\(?[0-9,.]+\\)?")[[1]]
> x
[1] "0"       "3,000"   "(500)"   "0"       "2.25"    "(1,200)"

将括号更改为否定:

x <- gsub("\\((.+)\\)","-\\1",x)
x
[1] "0"      "3,000"  "-500"   "0"      "2.25"   "-1,200"

然后 as.numeric() 或 taRifx::destring 完成(下一版本 destring 将默认支持否定，因此 keep 选项将是必需的):

And then as.numeric() or taRifx::destring to finish up (the next version of destring will support negatives by default so the keep option won't be necessary):

library(taRifx)
destring( x, keep="0-9.-")
[1]    0 3000  -500    0    2.25 -1200

或:

as.numeric(gsub(",","",x))
[1]     0  3000  -500     0     2.25 -1200