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Separate string with tag_string

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galaxy
galaxy on 5 Aug 2020
Commented: Stephen on 5 Aug 2020
Dear bros,
I want to separate long string which contains tags to each classify.
Example:
string = 'tag_A(this is tag A, it contains tag_B(this is tag_B, it contains tag_C(figure.png). This is still tag B). This is still tag A)';
output is array string or cell array such as:
this is tag A, it contains tag_B tag_A
this is tag_B, it contains tag_C tag_B
figure.png tag_C
This is still tag tag_B
This is still tag A tag_A
I used strfind, regexp, etc. but it does not work.
Do any one can help me?
Thank you so much

Accepted Answer

Stephen
Stephen on 5 Aug 2020
Edited: Stephen on 5 Aug 2020
This should get you started. Adjust as required.
str = 'tag_A(this is tag A, it contains tag_B(this is tag_B, it contains tag_C(figure.png). This is still tag B). This is still tag A)';
abc = cell(0,2);
xyz = cell(0,2);
rgx = '(\w+)\((.+)\)';
tkn = regexp(str,rgx,'once','tokens');
while numel(tkn)
tag = tkn{1};
[tkn,spl] = regexp(tkn{2},rgx,'once','tokens','split');
abc = [abc;spl(1),tag]; %#ok<AGROW>
xyz = [spl(end),tag;xyz]; %#ok<AGROW>
end
out = [abc;xyz(2:end,:)]
giving:
out =
'this is tag A, it contains ' 'tag_A'
'this is tag_B, it contains ' 'tag_B'
'figure.png' 'tag_C'
'. This is still tag B' 'tag_B'
'. This is still tag A' 'tag_A'
Note that regular expressions cannot easily match arbitrarily-nested pairs of parentheses. This answer will only work for input strings with nested parentheses, i.e. (...(...)...), as your example shows. It will not work for multiple parenthesis pairs on the same level of nesting, i.e. (...)(...).
  2 Comments
Stephen
Stephen on 5 Aug 2020
@galaxy: please show the expected output for your new example.

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