`isKey`

Tests whether keys are present in a containers.Map or dictionary.

Syntax

tf = isKey(M, key)

Returns true if key is a key of the map M.

tf = isKey(M, keys)

With a cell array of keys, tests each one and returns a logical array of the same size.

isKey is the safe way to guard a lookup, because reading a missing key with M(key) raises an error. Character keys are compared case-sensitively.

For a containers.Map it is written isKey(M, key); for a dictionary the same function applies and M.isKey(key) is also accepted.

M: A containers.Map or a dictionary object.
key, keys: A key, or a cell array of keys. Its type must match the key type of the map.

m = containers.Map({'a','b'}, [1 2]);
isKey(m, 'a')
isKey(m, {'a','z'})
if isKey(m, 'b'), disp(m('b')), end

Output

ans = logical
   1
ans = 1×2 logical array

   1   0
     2