Replace string with another value

What would be a good way replace a full string with first 3 letters of last word. For example '13 Jon Walker' with 'WAL' .

I have about 25 such replacements an this is indeed doable line-by-line "by-hand" using replace function, but that beats the purpose of MATLAB. Plus i might have more in future. I looked up regexprep too but it doesnt quite do that. OR have I missed it ? Is there a way I could apply a 'replace full string with first 3 letters of last word ' rule?

Thank you for your time in advance.

Answer 1

[Walter Roberson]

S = {'13 Jon Walker', '23 skidoo', '0 infinite way blvd'};
upper(regexprep(S, '^.*\s+(...).*', '$1'))

[klb]

Thank you this works! Could you please explain the meaning of qualifiers though.

Could you also clarify this if possible:

replace(13 Jon Walker,'WAL') returns '13 Jon Walker' not 'WAL' But

replace(13 Jon Walker,'WAL') returns 'WAL' .

Why would that be?