MATLAB: Varargin

cell arraysfunction

How can I check the input argument of a function to see if a specific string has been input? For example, I want to see if the user has input 'filename' in the function argument then the function reads the file name in the argument as well and writes the data into it otherwise doesn't write anything to any file.

myfunc(x, y, z, 'filename', 'mydata.txt') —> writes to mydata.txt

myfunc(x, y, z) —> does not write to any file

Actually, I have 10 possible cases and I want to be able to check which of those cases is in the input argument and based on that take the appropriate action like plot function which you can specify 'color', linewidth', 'linetype', and other plot properties arbitrarily.

Thanks, Ahmad

Best Answer

doc inputParser

With 10 possibilities, I think an inputParser object is the way to go. With only 1 or two possibilities, the inputParser might also be teh way to go.

Related Solutions

MATLAB: Listing the input arguments and values of a function in a Matrix

Yes, you can. Use this example:

InputArgument={'this is the string for the pattern','pattern'}
strfind(InputArgument{:});

MATLAB: Is the parameter-value argument pair incorrectly interpreted as an optional argument by the function INPUTPARSER in MATLAB 7.8 (R2009a)

The issue is that in the call

myFunction('param1','myval1')

the first argument 'param1' is interpreted as the "filename" argument. This is because the string 'param1' passes the validator for "filename" i.e.

   ischar('param1') == 1.

To prevent the parameter-value pair from being interpreted as an optional argument, a stricter validator should be defined for the "filename" argument is possible e.g. a validator that checks whether the argument ischar AND NOT equal to the string 'param1':

p.addOptional('filename',[],@(x) ischar(x) & ~strcmp(x,'param1'));

If there are more parameter-value pairs a validator function can be written which checks that the filename argument does not match any of the other argument names. An example of such a function would be:

function myFunction2(varargin)
      p = inputParser;
      p.addOptional('filename',[],@(x) strictValidator(x,p));
      p.addParamValue('param1',[],@ischar);
      p.addParamValue('param2',[],@ischar);
      p.parse(varargin{:});
      p.Results
function y=strictValidator(x,p)
      % Check whether the parameter ischar AND that it is NOT equal to the
      % name of any of the other parameters
      y = ischar(x) && ~any(strcmp(x,p.Parameters));

It should be noted that in the above example it is not possible to have "filename"='filename'. In other words the call

MyFunction2('filename')

will fail (because the string value 'filename' is also the name of an argument).

Best Answer

Related Solutions

MATLAB: Listing the input arguments and values of a function in a Matrix

MATLAB: Is the parameter-value argument pair incorrectly interpreted as an optional argument by the function INPUTPARSER in MATLAB 7.8 (R2009a)

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