How to use variable in a function?

Hello. I am trying to make a function which will take strings as input (where string contains 3 characters: 0, +, -) and any '+' or '-' character will be replaced by '0'.

Now i want to add a variable which determines how many '+' or '-' will be replaced by '0'. But i am not getting any idea how to add it in the function. I want to add this variable because input_strings and working_variable will be changing continously. Following is my code:

function replacement_result = replacement(input_strings, working_variable) 

 for i1 = 1 : size(input_strings,1)
    a = 0;
    for j1 = size(input_strings,2): -1 : 1
        if input_strings(i1,j1) == '0';
            a = a+1;
        else break,
        end
    end
    for k1 = (size(input_strings,2)-a): -1 : 1
        if input_strings(i1, k1) ~= '0'
            input_strings(i1, k1) = '0';
        else break,
        end
    end
end
replacement_result = input_strings;

If input_strings = [0+0-00-0+, +0+0-0+0-, -0-00-0+0], then if working_variable = 1, so replacement_result = [0+0-00-00, +0+0-0+00, -0-00-000]

If input_strings = [0+0-00-0+, +0+0-0+0-, -0-00-0+0], then if working_variable = 3, so replacement_result = [0+0000000, +0+000000, -00000000]

How can i add 'working_variable' in this function? Can any one please give me any idea?

Answer 1

[Geoff]

A lot of people may ignore this question because it's about programming rather than MatLab, specifically... But it would help you to know that MatLab has a lot of powerful functions and constructs that can do the work for you.

In your case, you can use cellfun to iterate over your cell of strings, find to search for the required number of +/- chars, and lambda functions to make the notation a little clearer.

function [replacement_result] = replacement(input_strings, working_variable) 

  replacement_result = cellfun( ...
          @(x) replace_n(x,working_variable), ...
          input_strings, 'UniformOutput', false );

end

function [str] = replace_n( str, n )
  f = @(x) find( x=='-' | x=='+', n, 'last' );
  str(f(str)) = '0';
end

Now you can do:

>> input_strings = {'0+0-00-0+', '+0+0-0+0-', '-0-00-0+0'};

>> replacement(input_strings,1)

ans = 

      '0+0-00-00'    '+0+0-0+00'    '-0-00-000'

>> replacement(input_strings,2)

ans = 

      '0+0-00000'    '+0+0-0000'    '-0-000000'

>> replacement(input_strings,10)

ans = 

      '000000000'    '000000000'    '000000000'

-g-

[Ayesa]

Thank you for your help. But as i don't have very good idea about MatLab, so it's hard for me to understand your code. But i am trying to understand this.

I have a question. Here, 'input_strings' is a matrix which contains characters.

But according to your code, 'input_strings' is a cell array. So, i used

xx = {input_strings} %% 'input_strings' is a matrix

yy = replacement(xx,1);

zz = cell2mat(yy)

zz = 0+0-00-0+

+0+0-0+00

-0-00-0+0

Which means it's not replacing '+' or '-' (from LHS) in each row. The result suppose to be:

zz = 0+0-00-00

+0+0-0+00

-0-00-0+0

But again many thanks.