Using Regex in Tableau but only getting Null values

Question

I'm trying to extract in Tableau the first occurrence of part of speech name (e.g. subst, adj, fin) located between { and : in every line from the below snippet:

{subst:pl:nom:m3=18, subst:pl:voc:m3=1, subst:pl:acc:m3=5}
{subst:sg:gen:m3=5, subst:sg:inst:m3=1, subst:sg:gen:f=1, subst:sg:nom:m3=1}
{subst:sg:nom:f=3, subst:sg:loc:f=2, subst:sg:inst:f=1, subst:sg:nom:m3=1}
{adj:sg:nom:m3:pos=2, adj:sg:acc:m3:pos=1, adj:sg:acc:n1.n2:pos=3, adj:pl:acc:m1.p1:pos=3, adj:sg:nom:f:pos=1}
{adj:sg:gen:f:pos=2, adj:sg:nom:n:pos=1}
{fin:sg:ter:imperf=5}

I use the following regular expression: {(\w+):(?:.*?)}$. Unfortunately my calculated field returns only Null's. Can anyone suggest me what am I doing wrong?

Answer 1

Tableau regex engine is ICU, and there are some differences between it and PCRE.

One of them is that braces that should be matched as literal symbols must be escsaped.

So you can try using this RegEx and let me know if that works for you.
 

REGEXP_EXTRACT([col], '^\{(\w+):.*\}$')