MATLAB: Regexp with a list of keywords

regexp

Hi everbody,
I'm aware regexp is a powerful tool, but I'm a newbie to this and I think my problem is an advanced one:
There is a list of keywords
keywords = {'alpha','basis','colic','druid','even'};
and I want regexp to find in a string all values after these keywords (followed by =).
For example:
str = 'basis=10,alpha=today,druid=none,even=odd,even=even';
gives
'today','10',[],'none',{'odd','even'}
Can you help me?

Best Answer

Using a simple lookaround assertion:
https://www.mathworks.com/help/matlab/matlab_prog/regular-expressions.html#brchk1t
>> keywords = {'alpha','basis','colic','druid','even'};
>> str = 'basis=10,alpha=today,druid=none,even=odd,even=even';
>> fun = @(k)regexp(str,sprintf('(?<=%s=)\\w+',k),'match');
>> out = cellfun(fun,keywords,'uni',0);
>> out{:}
ans = 
    'today'
ans = 
    '10'
ans = 
     {}
ans = 
    'none'
ans = 
    'odd'    'even'
Note that each cell of out is itself a cell array, with varying sizes. If you want to unnest the scalar cells, as you indicate in your question, then try this:
>> idx = cellfun(@isscalar,out);
>> out(idx) = [out{idx}]
out = 
    'today'    '10'    {}    'none'    {1x2 cell}
>> out{:}
ans =
today
ans =
10
ans = 
     {}
ans =
none
ans = 
    'odd'    'even'
https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html
https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists
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