The document provides an overview of Python data structures, focusing on lists and dictionaries. It details the characteristics, features, and operations associated with lists, such as adding, removing, and accessing elements, as well as the structure of dictionaries with key-value pairs. The information also includes practical examples of list manipulation and dictionary methods.

1. Python
Data structures
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3. Agenda
• List
• Dictionaries
• Tuples
• Strings
• Sets

4. List
• WhatisList?
• WherewecanuseofList?

5. What is List?
In Python, a list is a built-in data structure that represents a
collection of items. Lists are ordered, mutable (modifiable), and can
contain elements of different data types, including other lists. They
are defined by enclosing comma-separated values within square
brackets [ ].
Here's an example of a list:
• my_list = [1, 2, 3, 4, 5]
In this example, my_list is a list containing five integer
elements.

6. Lists offer several key features:
 Ordered: Lists maintain the order of elements as they are inserted. Elements are indexed starting from 0, so you
can access elements by their position.
 Mutable: Lists can be modified after creation. You can add, remove, or modify elements within a list.
 Heterogeneous: Lists can contain elements of different data types. For example, you can have integers, strings,
floats, or even other lists as elements of a single list.
 Dynamic: Lists in Python can grow or shrink dynamically as elements are added or removed. There's no need to
predefine the size of a list.
Here are some basic operations you can perform on lists:
o Accessing elements by index: my_list[0]
o Slicing: my_list[1:3]
o Appending elements: my_list.append(6)
o Removing elements: my_list.remove(4)
o Checking if an element exists: element in my_list
o Length of the list: len(my_list)
Lists are incredibly versatile and are used extensively in Python for a wide range of tasks, including storing collections
of data, representing sequences, and implementing various algorithms and data structures.

7.  We can use the append() method or extend() method to add elements to a list.
The append() method adds an object to the end of a list and extend() method
adds each element of an iterable object to a list. To update an existing element in a
list, assign the new value to that position using its index. See the examples.
 sample_list.append(1) :
 Output : [‘sample’, ‘list’, 45, ‘test’, 1]
 sample_list.append([1, 2]) :
 Output : [‘sample’, ‘list’, 45, ‘test’, [1, 2]]
 sample_list.extend([1,3,2]) :
 Output : [‘sample’, ‘list’, 45, ‘test’, 1, 3, 2]
 sample_list[0] = ‘new_val’
 Output : [‘new_val’, ‘list’, 45, ‘test’]
List..

8.  To delete elements, we can use del statement.
 del sample_list[2] : //deletes element with index 2.
  The sample_list.insert() method will insert an element at a particular position. The format
is,
 sample_list.insert(i, x). //It will insert element ‘x’ at position ‘i’.
 The method, sample_list.remove(x) will remove the first element in the list whose value is ‘x’.
 sample_list.pop(i) removes the item at the given position in the list, and return it
 If no index is specified, sample_list.pop() removes and returns the last item in the list.
 sample_list.clear() removes all the items from the list.
 It is equivalent to del sample_list[:].
 sample_list.count(x) will return the number of times ‘x’ appears in the list.
 The reverse() method can be used to reverse the elements in a list
 copy() will create another copy of the list.
List..

9. • A dictionary contains a sequence of key-value pairs. We can access keys and values of a dictionary
independently. Dictionary elements are enclosed by curly brackets.
• d = {‘key1’: ‘first’, ‘key2’: [6, 7] }
• d.keys() will list all the keys and d.values() will list all the values of the dictionary.
• In addition to keys and values methods, there is also items() method which returns a list of items in
the form (key, value). The items are not returned in any particular order.
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