Dictionary
Methods in Python
* There are various methods to
process the elements of a dictionary
* These methods are used for
retrieving and manipulating the contents of a dictionary
* These various methods have
been summarised in the given description table
===================================
Methods
to process Dictionaries in Python
===================================
1) clear()
dict.clear()
This method removes all the
key-value pairs from the dictionary 'd' .
2) copy()
d1
= dict.copy()
This method copies all the elements
from the dictionary 'd' into a new dictionary object 'd1' .
3) fromkeys()
dict.fromkeys(s[,v])
This creates a new dictionary
with keys from a given sequence 's' and all the values set to 'v'
4) get()
dict.get(k[,v])
This returns all the values
associated with the key 'k' . If the key is not found , then it returns 'v'
5) items()
dict.items()
This returns an object that
contains key-value pairs of dictionary item 'dict' . The key value pairs are
stored as tuples in the objects .
6) keys()
dict.keys()
This returns a sequence of keys
from the dictionary object "dict" .
7) values()
dict.values()
This returns a sequence of
values from the dictionary object "dict"
8) update()
dict.update(x)
This method adds all elements
from the dictionary 'x' to the dictionary item object 'dict'
9) pop()
dict.pop(k[,v])
This method removes the key 'k'
and its associated value from the dictionary object "dict" and
returns the value associated with that key "v" is returned . If the
key is not found and "v" is not mentioned then "KeyError"
exception error is raised .
10) setdefault()
dict.setdefault(k[,v])
If the key 'k' is found , then
its value is returned and if the key is not found , then the k,v pair is stored
into the dictionary 'd'. In the given program , we are going to retrieve the
keys from a dictionary object using the keys() method . The keys() method
returns dict_keys object that contains only keys . We will be also able to
retrieve the values from the dictionary object using the values() method . This
method "values()" returns all the values in the form of a dict_values
object . Similarly , the items() method can be used to retrieve all the
key-value pairs into the "dict_items"
method can be used to retrieve
all the key-value pairs into the "dict_items" object .
==============================================
Program
A Python program to retrieve
keys , values and key-value pairs from a dictionary object
# dictionary methods - create a
dictionary with employee details
dict
=
{
'Name' : 'D001' ,
'Id' : '001',
'Salary' : 1000
}
# print the entire dictionary
print(dict)
# display only keys
print("
values in dict = ", dict.values())
# display both key and value
pairs as tuples
print("
Items in Dictionary =", dict.items())
Output
:
{
'Name' : 'D001' ,
'Id' : '001',
'Salary' : 1000
}
Keys
in dict =dict_keys(['Name','Id','Salary'])
Values
in dict = dict_values(['D001','001','1000'])
Items
in dict = dict_items([('Name','D001'),('Id',001),('Salary',1000)])
In the given program, we are
creating a dictionary by entering the elements from the keyboard and when the
user enters the elements from the keyboard inside the curly braces , then the
values inside the dictionary object are treated as key value pairs of a
dictionary by using the eval() function . Once the elements are entered , one
can find the sum of the values using the sum() function over the values of the
dictionary .
The screenshot for the used code implemented over Jupyter Notebook is given as below :
