Values are unordered pair of key-value pairs
Each value has a corresponding key. Thus there exists a one-to-one relation between them
You cannot get a key by value, as otherwise
Keys are immutable but values can either be immutable or mutable
Dictionary cannot have a duplicate key thus a one-to-one relation must always exist between key and value. Assigning a value to an existing key will wipe out the old value
>>> d = {“Hello”:10, “world”:20}
>>> d
{‘world’: 20, ‘Hello’: 10}
>>> d[“Hello”]
10
>>> d[“Hello”] = 30
>>> d
{‘world’: 20, ‘Hello’: 30}
- Dictionaries support the following in-built methods, but are not limited to these:
d[k] retrieves a value from a dictionary
d[k]=x sets a value in the dictionary
d.has_key(k) tests for the presence of a keyword
d.get(k, d) returns a default if a key is not found
d.keys() returns a list of keys from a dictionary
d.values() returns a list of values