how isKey searches keys of an associative map (containers.Map)

If M is an associative map (containers.Map) and k is a potential key, what exactly happens when I execute isKey(M,k)? It seems that the output of keys(M) is ordered by whatever the "natural" order is for M's particular type of key. Does that mean that isKey does a binary search? Or does isKey do a linear search? Or does isKey do something else? Or does it depend on details that I didn't include here?

Thanks!

Answer 1

[Samhitha]

Hi @Herbert Triceratops,

While executing isKey(M, k) on a containers.Map in MATLAB, the function checks for the existence of the key using a hash table lookup, not a linear or binary search. The order of keys returned by keys(M) is just for display and does not affect how “isKey” works. The key lookup is generally very fast average-case constant time and independent of key type or order.

For more details go through the following documentation

https://www.mathworks.com/help/matlab/ref/containers.map.iskey.html