Is there an Octave equivalent of Matlab's `contains` function?

Question

Is there an equivalent of MATLAB's contains function in Octave? Or, is there a simpler solution than writing my own function in Octave to replicate this functionality? I am in the process of switching to Octave from MATLAB and I use contains throughout my MATLAB scripts.

Answer 1

Let's stick to the example from the documentation on contains : In Octave, there are no (double-quoted) strings as introduced in MATLAB R2017a. So, we need to switch to plain, old (single-quoted) char arrays. In the see also section , we get a link to strfind . We'll use this function, which is also implemented in Octave to create an anonymous function mimicking the behaviour of contains . Also, we will need cellfun , which is available in Octave, too. Please see the following code snippet:

% Example adapted from https://www.mathworks.com/help/matlab/ref/contains.html

% Names; char arrays ("strings") in cell array
str = {'Mary Ann Jones', 'Paul Jay Burns', 'John Paul Smith'}

% Search pattern; char array ("string")
pattern = 'Paul';

% Anonymous function mimicking contains
contains = @(str, pattern) ~cellfun('isempty', strfind(str, pattern));
% contains = @(str, pattern) ~cellfun(@isempty, strfind(str, pattern));

TF = contains(str, pattern)

The output is as follows:

str =
{
  [1,1] = Mary Ann Jones
  [1,2] = Paul Jay Burns
  [1,3] = John Paul Smith
}

TF =
  0  1  1

That should resemble the output of MATLAB's contains .

So, in the end - yes, you need to replicate the functionality by yourself, since strfind is no exact replacement.

Hope that helps!

---

EDIT: Use 'isempty' instead of @isempty in the cellfun call to get a faster in-built implementation (see carandraug's comment below).

Answer 2

I'm not too familiar with MuPad functions, but it looks like this is reinventing the ismember function (which exists in both Matlab and Octave).

Eg

ismember( {'jim', 'stan'}, {'greta', 'george', 'jim', 'jenny'} )
% ans = 1  0

ie 'jim' is a member of { 'greta' , 'george' , 'jim' , 'jenny' }, whereas 'stan' is not.

Furthermore, ismember also supports finding the index of the matched element:

[BoolVal, Idx] = ismember( {'jim', 'stan'}, {'greta', 'george', 'jim', 'jenny'} )
% BoolVal = 1  0
% Idx     = 3  0

Answer 3

Personally I use my own implementation, which returns 1 if a string str contains entire substring sub :

function res = containsStr(str, sub)
res = 0;

strCharsCount = length(str);
subCharsCount = length(sub);

startCharSub = sub(1);

% loop over character of main straing
for ic = 1:strCharsCount
    currentChar = str(ic);
    % if a substring starts from current character
    if (currentChar == startCharSub)
        %fprintf('Match! %s = %s\n', currentChar, startCharSub);
        
        matchedCharsCount = 1;
        % loop over characters of substring
        for ics = 2:subCharsCount
            nextCharIndex = ic + (ics - 1);
            % if there's enough chars in the main string
            if (nextCharIndex <= strCharsCount)
                nextChar = str(nextCharIndex);
                nextCharSub = sub(ics);
                if (nextChar == nextCharSub)
                    matchedCharsCount = matchedCharsCount + 1;      
                end
            end
        end
        
        %fprintf('Matched chars = %d / %d\n', matchedCharsCount, subCharsCount);
        
        % the substring is inside the main one
        if (matchedCharsCount == subCharsCount)
            res = 1;  
        end
    end
end

end