Updating, Delete Dictionary Elements & Tuples, Accessing Values in Tuples & Lists.

 Updating Dictionary

You can update a dictionary by adding a new entry or a key-value pair, modifying an existing entry, or deleting an existing entry as shown below in the simple example −

When the above code is executed, it produces the following result −

dict['Age'] : 8

dict['School'] : DPS School

Delete Dictionary Elements

You can either remove individual dictionary elements or clear the entire contents of a

dictionary. You can also delete the entire dictionary in a single operation. To explicitly remove an entire dictionary, just use the del statement. Following is a simple example −

Accessing Values in Tuples

To access values in a tuple, use the square brackets for slicing along with the index or

indices to obtain the value available at that index. For example −

When the above code is executed, it produces the following result −

tup1[0] : physics

tup2[1:5] : [2, 3, 4, 5]

Updating Tuples

Tuples are immutable which means you cannot update or change the values of tuple

elements. You are able to take portions of existing tuples to create new tuples as the

following example demonstrates −

When the above code is executed, it produces the following result −

(12, 34.56, 'abc&', 'xyz')

Delete Tuple Elements

Removing individual tuple elements is not possible. There is, of course, nothing wrong

with putting together another tuple with the undesired elements discarded.
To explicitly remove an entire tuple, just use the del statement. For example −

This produces the following result. Note an exception raised, this is because after del

tup tuple does not exist anymore −

('physics', 'chemistry', 1997, 2000)

After deleting tup :

Traceback (most recent call last):

File 'test.py', line 9, in <module>

print tup;

NameError : name 'tup' is not defined

Accessing Values in Lists

To access values in lists, use the square brackets for slicing along with the index or

indices to obtain value available at that index. For example −

When the above code is executed, it produces the following result −

list1[0] : physics

list2[1:5] : [2, 3, 4, 5]

Updating Lists

You can update single or multiple elements of lists by giving the slice on the left-hand

side of the assignment operator, and you can add to elements in a list with the

append() method. For example −

Note − append() method is discussed in subsequent section.

When the above code is executed, it produces the following result −

Value available at index 2 :

1997

New value available at index 2 :

2001

Delete List Elements

To remove a list element, you can use either the del statement if you know exactly

which element(s) you are deleting or the remove() method if you do not know. For

example −

When the above code is executed, it produces the following result −

['physics', 'chemistry', 1997, 2000]

After deleting value at index 2 :

['physics', 'chemistry', 2000]

Note − remove() method is discussed in a subsequent section.