Matlab: Specified value type does not match the type expected for this container

dictionary, matlab

Solution

If you do

help containers.Map

you get a section which says

Valid values for vType are the strings: `'char', 'double', 'single',` `'int8', 'uint8', 'int16', 'uint16', 'int32', 'uint32', 'int64',` `'uint64', 'logical',` or `'any'`. The order of the key type and value type arguments is not important, but both must be provided.

You could use:

containers.Map('KeyType','char', 'ValueType','any')

However, the behaviour that you probably want is:

myMap = containers.Map(keySet, num2cell(valueSet))

That will give you one an object of type myClass when you put in the correct key. This is most likely because `containers.Map` is expecting a cell array of custom objects rather than an object array.

Your code would look clearer like this:

valueSet = cell(1,4);
keySet = cell(1,4);

for i=1:4
   valueSet{i} = myClass();
   keySet{i} = valueSet{i}.name;
end

map = containers.Map(keySet, valueSet);

Problem

I am experiencing problems to use the containers.Map of matlab. Here an example of my issue: When I try to build the map of an array of myClass instance with a cellarray of keys defined as : ``` valueSet = myClass.empty(4,0); keySet = cell(1,4); for i=1:4 valueSet(i) = myClass(); keySet{i} = valueSet(i).name; end map = containers.Map(keySet, valueSet); ``` with ``` classdef myClass < handle properties name; end methods function self = myClass() self.name = randstr(10); end function output = randstr(n) symbols = ['a':'z' 'A':'Z' '0':'9']; nums = randi(numel(symbols),[1 n]); output = symbols (nums); end end end ``` I get this error: ``` Error using containers.Map Specified value type does not match the type expected for this container. ``` However the matlab documentation says : mapObj = containers.Map(keySet,valueSet) constructs a Map that contains one or more values and a unique key for each value. keySet 1-by-n array that specifies n unique keys for the map. If n > 1 and the keys are strings, keySet must be a cell array. valueSet : 1-by-n array of any class that specifies n values for the map. The number of values in valueSet must equal the number of keys in keySet. I also tried to specified the class type but it raised also an error: ``` containers.Map('KeyType','char', 'ValueType','myClass') Error using containers.Map Unsupported ValueType 'myClass' specified. See documentation for valid value types. ``` So I don't understand... if containers.Map is working for any class, why is not working for myClass ?

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