CODEWITHSUNDEEP
matlabcontainersequalityequivalence
Anton Daneyko
Anton Daneyko

Reputation: 6503

In Matlab, how do I compare two container.Map objects element-wise?

I have two container.Map objects, with identical keys and values. Is there a Matlab function, that is going to return true in the following scenario:

>> m1 = containers.Map('hi', 'ho');
>> m2 = containers.Map('hi', 'ho');
>> m1 == m2

ans =

     0

Upvotes: 3

Views: 968

Answers (2)

RTL
RTL

Reputation: 3587

isequal is your friend here...

From the help for isequal

When comparing handle objects, use EQ or the == operator to test
whether objects are the same handle. Use isequal to test if objects
have equal property values, even if those objects are different
handles.

and as mentioned by @gire containers.Map is linked to the handle class

So with the simple maps given

isequal(m1,m2)

ans =

     1

Upvotes: 1

gire
gire

Reputation: 1105

The containers.Map class inherits from the handle class which means that the == operator will only return true in the following case:

m1 = containers.Map('hi', 'ho');
m2 = m1;
m2 == m1

Handles behave like a pointer (to some extent!).

If you want to compare two different maps you need to loop their elements and compare one by one. For example:

keys1 = m1.keys;
keys2 = m2.keys;

% // If the keys are not equal there is no reason to loop
if ~isequal(keys1, keys2)
    disp('Maps are not equal');
    return;
end

% // Since at this point it is known that keys1 == keys2, keys1 is used as a
% // base
results = false(size(keys1));
for i = 1:length(keys1)
    results(i) = ms1(keys{i}) == ms2(keys{i});
end

if all(results)
    disp(';aps are equal');
else
    disp('Maps are not equal');
end

Upvotes: 1

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