How is the efficiency of data search in a hash table evaluated?

The efficiency of data search in a hash table is usually evaluated by the access time to an element. On average, the search is performed in O(1) — constant time, which means a very fast operation regardless of the size of the table.

This is achieved because the key is transformed into an array index using a hash function. However, in the worst case (for example, in collisions), the time can degrade to O(n), where n is the number of elements in the table.

In Python, a dictionary (dict) is implemented as a hash table, which provides quick access to values by key:

my_dict = {'apple': 1, 'banana': 2}
value = my_dict.get('apple')  # Fast access to the value