Proper use of regexprep

I want to remove the consonants of a string, using regexprep. How can I modify the initial string s1 with a string s2?

    s2 = regexprep(s1,'qwrtpsdfghjklzxcvbnmQWRTPSDFGHKLZXCVBNM','')

[Guillaume]

I don't understand the question. Your code already remove the consonants (assuming basic latin alphabet only). What more do you want?

[per isakson]

Your statement is lacking the square brackets. Try

s2 = regexprep(s1,'[qwrtpsdfghjklzxcvbnmQWRTPSDFGHKLZXCVBNM]','')

Answer 1

[KL]

use the ^ operator. It should simply be,

 s2 = regexprep(s1,'[^aeiou]','')

documentation explains it clearly here: https://de.mathworks.com/help/matlab/ref/regexprep.html

[GEORGIOS BEKAS]

it works, but how do I specify what it should be removed?

[GEORGIOS BEKAS]

also it removes the spaces and the capital letters. :/

[KL]

it removes every character except what you mention inside the square brackets following ^ sign.

 s2 = regexprep(s1,'[^aeiouA-Z]','') %ignores capital letters (A-Z)
 s2 = regexprep(s1,'[^aeiouA-Z\s]','') %ignores white spaces as well

I gave you the link to documentation. It explains much more and guess what, even with examples!

Answer 2

[the cyclist]

Can you just do

s1 = s2;

after that? Or just

s1 = regexprep(s1,'qwrtpsdfghjklzxcvbnmQWRTPSDFGHKLZXCVBNM','');

directly, eliminating creating the intermediate variable s2?