R：在特定单词后提取数字

Question

I have a column like below:

C1
we-23 pcs,qw-4 pcs
we-30 pcs
er-21 pcs,we-2 pcs
tr-23 pcs
we-0 pcs, re-2 pcs
we-0 pcs
NA

I want to extract the quantities of "we" in numeric format, with NAs preserved and no character(0). I used:

C2 <- as.numeric(str_extract_all(str_extract_all(C1, "we-*\\d+"), "\\d+"))

Result:

C2
23
30
2
0
0
0
NA

However, I want to get the tr-23 pcs entry to be different than we-0 pcs. So I am using another logical column to find "we" in C1. Is there a better way to do this?

Answer 1

You may use

C2 <- as.numeric(str_extract(C1, "(?<=we-)\\d+"))

See the regex demo .

Pattern details :

• (?<=we-) - a positive lookahead that matches a position that is preceded with we-
• \\d+ - 1+ digits.