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.
getalso can be used to access a value of particular element indictby 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
keysand all the values in the form of list like object by usingvalues. - We can also use
itemsto convert adictinto 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.
- Creating a dict object
In [1]:
d = {'id': 1, 'first_name': 'Scott', 'last_name': 'Tiger', 'amount': 1000.0}
- Accessing one of the element with key id from
dict.
In [2]:
d['id']
Out[2]:
1
- Accessing another element with key first_name from
dict.
In [3]:
d['first_name']
Out[3]:
'Scott'
In [4]:
d['commission_pct'] # throws key error
--------------------------------------------------------------------------- KeyError Traceback (most recent call last) Input In [4], in <cell line: 1>() ----> 1 d['commission_pct'] KeyError: 'commission_pct'
- We can also use
getto get the value by passing the key as argument to it.
In [5]:
d.get?
Signature: d.get(key, default=None, /) Docstring: Return the value for key if key is in the dictionary, else default. Type: builtin_function_or_method
In [6]:
d.get('first_name')
Out[6]:
'Scott'
- If the key does not exists it will return
None(unliked['commission_pct']which threw key error.
In [7]:
d.get('commission_pct') # Returns None
- You can pass default value as second argument to
get. If the key exists it will return the value fromdict, if not it will return the default value which is passed as second argument.
In [8]:
d.get('first_name', 'Some First Name')
Out[8]:
'Scott'
In [9]:
d.get('commission_pct', 0)
Out[9]:
0
In [10]:
d.keys?
Docstring: D.keys() -> a set-like object providing a view on D's keys Type: builtin_function_or_method
In [11]:
d.keys() # returns all the keys in set like object (as keys are unique)
Out[11]:
dict_keys(['id', 'first_name', 'last_name', 'amount'])
In [12]:
d.values?
Docstring: D.values() -> an object providing a view on D's values Type: builtin_function_or_method
In [13]:
d.values() # returns all the values in list like object.
Out[13]:
dict_values([1, 'Scott', 'Tiger', 1000.0])
In [14]:
d.items?
Docstring: D.items() -> a set-like object providing a view on D's items Type: builtin_function_or_method
In [15]:
d.items()
# returns all the items in set like object.
# Each item will be of type tuple
# Each tuple will contain key from the dict followed by corresponding value
Out[15]:
dict_items([('id', 1), ('first_name', 'Scott'), ('last_name', 'Tiger'), ('amount', 1000.0)])
- We can convert keys or values or items to list and perform any list operations.
In [16]:
list(d.items())[0] # first tuple from the list of items from dict
Out[16]:
('id', 1)
In [17]:
list(d.items())[1] # second tuple from the list of items from dict
Out[17]:
('first_name', 'Scott')
In [18]:
type(list(d.items())[1])
Out[18]:
tuple