Accessing Elements - dict

Let us see how we can access elements from the dict using Python as programming language.

  • We can access a value of a particular element in dict by passing key d[key]. If the key does not exists, it will throw KeyError.

  • get also can be used to access a value of particular element in dict by passing key as argument. However, if key does not exists, it will return None.

  • We can also pass a default value to get.

  • We can get all the keys in the form of set like object by using keys and all the values in the form of list like object by using values.

  • We can also use items to convert a dict into a set like object with pairs. Each element (which is a pair) in the set like object will be a tuple.

  • Let us see few examples.

d = {'id': 1, 'first_name': 'Scott', 'last_name': 'Tiger', 'amount': 1000.0}

d['id']

1

d['first_name']

'Scott'

d['commission_pct'] # throws key error

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-5-583ad3d358bd> in <module>
----> 1 d['commission_pct'] # throws key error

KeyError: 'commission_pct'

d.get?

Docstring: D.get(k[,d]) -> D[k] if k in D, else d.  d defaults to None.
Type:      builtin_function_or_method

d.get('first_name')

'Scott'

d.get('commission_pct') # Returns None

d.get('first_name', 'Some First Name')

'Scott'

d.get('commission_pct', 0) 

0

d.keys?

Docstring: D.keys() -> a set-like object providing a view on D's keys
Type:      builtin_function_or_method

d.keys()

dict_keys(['id', 'first_name', 'last_name', 'amount'])

d.values?

Docstring: D.values() -> an object providing a view on D's values
Type:      builtin_function_or_method

d.values()

dict_values([1, 'Scott', 'Tiger', 1000.0])

d.items?

Docstring: D.items() -> a set-like object providing a view on D's items
Type:      builtin_function_or_method

d.items()

dict_items([('id', 1), ('first_name', 'Scott'), ('last_name', 'Tiger'), ('amount', 1000.0)])

list(d.items())[0]

('id', 1)

list(d.items())[1]

('first_name', 'Scott')

type(list(d.items())[1])

tuple
Accessing Elements - tuples Manipulating dict