MATLAB: Set up a subkey for containers.map class

containers.map

I am curious is it possible for a map to have keys and according subkeys for a specific value? For example, if the keys are blue, red and grey, can I further divide each color into dark and light? Thanks in advance. 🙂

Best Answer

See my multidimensional map class.

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MATLAB: Error using containers.Map

Note: I would avoid having variable names that only differ by one being plural and singular unless one was just a scalar element of the plural container.

As per Walter's answer, it seems you have not shown all the code, since your first loop is useless if the map is not filled.

Assuming the map declaration you've shown is the actual you use:

variables = containers.Map();

then it uses 'char' as the key type. However, you then have:

for keys = 1:numel(variables)
  if strcmp(variables(keys), 'Constant')

There are two issues here. For starter, since variables is a map, numel(variables) is just 1. Perhaps you meant, variables.Count. Secondly, keys will be a double. As said the key type is 'char', not 'double', so you can't actually use your keys as a key into the map. Hence the error message.

Perhaphs, you meant:

for elementidx = 1 : variables.Count
    if strcmp(variables.values{elementidx}, 'Constant')  %if you want to compare the value
    %or maybe
    if strcmp(variables.keys{elementidx}, 'Constant')   %if you want to compare the actual key

MATLAB: Passing containers.Map to MEX file

Hi,

passing the variable is easy: just use it ;-). O.K., serious now. Passing is not the problem but doing anything meaningful will be. You will be able to call methods using mexCallMATLAB, e.g.,

/* cmap.c */
void mexFunction(int nlhs, mxArray* plhs[], 
                 int nrhs, const mxArray* prhs[]) {
   mexCallMATLAB(1, plhs, 2, prhs, "isKey");
}

and in MATLAB:

x = containers.Map('foo', 42);
v = cmap(x, 'foo');

Otherwise: pass x.keys and x.values to mex function and work with the two cell arrays ...

Titus

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Related Solutions

MATLAB: Error using containers.Map

MATLAB: Passing containers.Map to MEX file

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