Here you'll find some examples for dictionaries.

Initialization

# open brace
dict_1 = { 
    "shirts": 15,
    "pants": 20,
    "socks": 12
}
# or (only if key values are strings)
dict_2 = dict(
    shirts=15,
    pants=20,
    socks=12
)
# or (tuple list)
dict_3 = dict([ 
    ( "shirts", 15 ), 
    ( "pants", 20 ),
    ( "socks", 12 )
])
print(dict_1, dict_2, dict_3)

Indexing (Not really)

Dictionaries are not indexed the way lists are. (Unless you make it do so)

# Using dict 1 from the example above
# No indexing like lists
>>> dict_1[0]
Traceback (most recent call last):
  File "<pyshell#>", line 1, in <module>
    dict_1[0]
KeyError: 0
# Key value retrieval
>>> dict_1['shirts']
15

Access values in dictionaries by putting the key of the obect where you'd put your index while indexing a list.

    >>> any_dictionary['someKey']
    someValue

Keys/Values

Some restrictions on keys and values

Keys

• Keys are unique!
• Only immutable types. (So tuples can be used as keys)

Values

• No restrictions on values.
• Not unique, values can repeat.
• Put anything you want inside a dictionary value.

Insertion/Deletion

# Using dict 1 from the example above
# Insert by creating a new key and assigning it a value
>>> dict_1['ties'] = 10
{'shirts': 15, 'pants': 20, 'socks': 12, 'ties': 10}
# Modify variables by accessing its value first (reassign the value at key after)
>>> dict_1['ties'] += 15
{'shirts': 15, 'pants': 20, 'socks': 12, 'ties': 25}
# Delete obects by using 'del' keyword or by 'pop()'
>>> del dict_1['ties']
{'shirts': 15, 'pants': 20, 'socks': 12}
>>> dict_1.pop('shirts')
{'pants': 20, 'socks': 12}

Operations

>>> dict_1['ties'] = 15
{'pants': 20, 'socks': 12, 'ties': 10}
>>> 'ties' in dict_1 # in operator works like 
True
>>> len(dict_1)
3

The in operator works like lists but specifically for keys. The len function gives the number of key value pairs in the dictionary.

Methods

# .items() -> list of tuples (key, value)
>>> list(dict_1.items())
[('pants', 20), ('socks', 12), ('ties', 15)]
# .get( <key> ) -> value
>>> dict_1.get('pants')
20
# .clear()
>>> dict_1.clear()
{}
# .keys() -> list of keys
>>> dict_1.keys()
['pants','socks','ties']
# .values() -> list of ALL values
>>> dict_1.values()
[20,12,15]