keep original string in the replacement text R

Question

I want to match some expressions and quote them;

input: gene_id TM_000000132331; transcript_id ENST_0000001435435.2;

output: gene_id "TM_000000132331"; transcript_id "ENST_0000001435435.2";

how can I do it? using gsub or str_replace, whatever..?

Answer 1

In the gsub call, parenthesize the part of pattern you want to enclose in double quotes, and use \1 to refer to matched substrings in replacement :

x <- "gene_id TM_000000132331; transcript_id ENST_0000001435435.2;"
gsub("(\\S+);", "\"\\1\";", x)
## [1] "gene_id \"TM_000000132331\"; transcript_id \"ENST_0000001435435.2\";"

You can search "backreference" in ?regex for more details.