How to capture the substring of a dynamic multivalued field?

[GaryZ]

I am looking to create an acronym from a dynamic string, by capturing the first letter of each broken substring

How do I write the script, so I can capture whatever number of substrings gets generated from the original string?

ie. "Hello_World_Look_At_Me" => "HWLAM"

"Hello_World" => "HW"

I'm thinking of doing the following, but this seems to be pretty lengthy.  Would like to know if there's a more efficient way of getting this done.

| eval txt1 = "Hello_World_Look_At_Me"

| eval tmp = split(txt1, "_")

| eval new_word = substr(mv_index(tmp,1), 1) + ...

[GaryZ]

Thanks!!! @ITWhisperer 

[ITWhisperer · Accepted solution]

Assuming words are always made of alphabetic letters, try something like this

| rex max_match=0 field=txt1 "(?<initial>[a-zA-Z])[a-zA-Z]*_?"
| eval new_word=mvjoin(initial,"")