Python dict (Dictionary) Data Type

Python dict (dictionary) is a collection of key-value pairs.

>>> quote = {
...     'open' : 9.54, 
...     'high' : 9.71, 
...     'low' : 9.49, 
...     'close' : 9.62
... }
...
>>> quote
{'open': 9.54, 'high': 9.71, 'low': 9.49, 'close': 9.62}
>>> type(quote)
<class 'dict'>

You can find a value by its key:

>>> quote['close']
9.62

You can also change a value by its key:

>>> quote['close'] = 9.63
>>> quote
{'open': 9.54, 'high': 9.71, 'low': 9.49, 'close': 9.63}

You can add a new key-value pair in the same way:

>>> quote['volume'] = 10855
>>> quote
{'open': 9.54, 'high': 9.71, 'low': 9.49, 'close': 9.63, 'volume': 10855}

Keys must be unique, values can be duplicate.

>>> quote = {
...     'open' : 9.71, 
...     'high' : 9.71, 
...     'low' : 9.49, 
...     'close' : 9.62
... }

Values can be of different types.

>>> quote = {
...     'open' : 999999, 
...     'high' : None, 
...     'low' : 'No idea', 
...     'close' : 9.62
... }

Keys can also be of different types (they must still be unique).

>>> various = {
...     'open' : 'This key is a string',
...     'high' : 'This key is another string',
...     123 : 'This key is an int', 
...     123.456 : 'This key is a float', 
...     True : 'This key is a bool'
... }