dictionaries

dictionary

-data structure that consists of key value pairs

-known as associative arrays in some other language, are indexed by keys rather than a numerical index

-keys can be immutable type: number, strings, booleans, etc.

-values can be whatever you want

-empty dict= {}

-dict()

-retrieve values using dict[key]

dict.get()

the get() method will look for a given key in a dictionary. if the key exists, it will return the corresponding value. otherwise it returns None

pop()

method accepts a key and will delete the corresponding key-value pair in the dictionary. it returns the deleted value

popitem()

deletes the most recently added key-value pair. it returns the item as a tuple

clear()

deletes all items from a dictionary. it returns None

del statement

remove items from a dictionary. not a method

update

update method will update a dictionary using the key value pairs from a second dictionary, passed as the argument

** trick

we can use two stars ** to combine multiple dictionaries into a new resulting dictionary

dict union

python 3.9 added the diction union operator(|) it will return a new dict containing the items from the left and right dicts. in the case of duplicated keys, the right side “wins”