By consulting the MATLAB External Interfaces documentation, the Python dict type is essentially the same interface as a containers.Map. You need to use the values function to extract the value that you want for a certain key. As such, you would call values like so, given that your Python dictionary is stored in A and you want to use '2' as the key to index into your dictionary:
val = values(A, '2');
As such, val would contain what the associated value is with the key of '2'. MATLAB also has the ability to use multiple keys and it would return multiple values - one per key. Therefore, you could also do something like this:
val = cell(values(A, {'1', '2', '3'}));
val would be a three element cell array, where each element is the value for the associated keys that you input in. It is imperative that you convert the output of values into a cell array, because this would normally be a list in Python. In order to use these results in MATLAB, we need to convert to a cell.
Therefore, val{1} would be the dictionary output when you used '1' as the key. Similarly, val{2} would be the dictionary output when you used '2' as the key and so on.
Here are some more operations on a containers.Map object for you. If you want all of the keys in a dictionary, use the keys function:
k = keys(A);
If you were to just use values with the dictionary by itself, like so:
val = cell(values(A));
It would produce all values for every key that exists in your dictionary stored into a cell array.
If you wanted to update a particular key in your Python dictionary, use the update function:
update(A,py.dict(pyargs('4',5.677)));
Here, we use the dictionary A, and update the key-value pair, where the key is '4' and the new value is 5.677.
