Python Data Structures and Algorithms

Counter objects

Counter is a subclass of a dictionary where each dictionary key is a hashable object and the associated value is an integer count of that object. There are three ways to initialize a counter. We can pass it any sequence object, a dictionary of key:value pairs, or a tuple of the format (object = value, ...), for example:

We can also create an empty counter object and populate it by passing its update method an iterable or a dictionary, for example:

Notice how the update method adds the counts rather than replacing them with new ...