A Python List is used to Store various datatypes in a sequence. A list is a grouping of values or items of various types. Because Python lists are mutable types, we can change their elements after they have been created. The list’s items are separated with commas (,) and encased in square brackets [].
One of the four built-in data types in Python for storing data collections is the list; the other three are the tuple, set, and dictionary, each of which has a unique purpose.
Python lists are the same as arrays defined in other languages, such as Java’s ArrayList and C++’s vector. Using the symbol [] and commas to separate each item, a list is a collection of items.
Creating a List in Python:
In Python, a list is made by putting elements between [ ] separated by commas.
Example:
List1 = ["apple", "mango", "cherry"]
List2 = ["horse", "elephant", "tiger"]
print(list1)
print(list2)
Output:
[‘apple’, ‘mango’, ‘cherry’]
[‘horse’, ‘elephant’, ‘tiger’]
The complexity of Creating the list
Time Complexity: O(1)
Space Complexity: O(n)
In the above example, we created a list of fruit and animals and print it.
Items in List:
- Items in list can be accessed by the index
- List can store multiple type of items
- List items allows duplicate values
- List items are changeable
Multiple values in a List:
A list having the elements of different values
Example
list = [5, 6, 'Tech', 4, 'For', 6, 'Study']
print("\n printing the list having different values")
print(list)
Output:
printing the list having different values
[5, 6, ‘Tech’, 4, ‘For’, 6, ‘Study’]
Ordered List: Lists are called ordered if the items are arranged in a specific order that will not change.
Changeable: We can change the list by adding and removing the items after the creation of a list
Duplicates: The list can have multiple items , some multiple items having the dplicate value are allowed in python.
Example
trending = ["tech", "study", "has", "the", "best", "content", "related","to", "tech"]
print(trending)
print(type(trending)) // Using type() we will know about the type of the list
Output:
[‘tech’, ‘study’, ‘has’, ‘the’, ‘best’, ‘content’, ‘related’, ‘to’, ‘tech’]
<class ‘list’>
List Operations
- Repetition
- Length
- Concatenation
- Iteration
Repetition: The list of elements can be repeated multiple times
Example:
list1 = [5, 6, 7, 8, 9]
repeat = list1 * 2
print(repeat)
Output:
[5, 6, 7, 8, 9, 5, 6, 7, 8, 9]
Length: It will print the length of the list
Example:
list = [5, 6, 'Tech', 4, 'For', 6, 'Study']
print(len(list) )
Output:
7
Concatenation:
It will concatenate the two or more list in a single list.
list1 = [5, 6, 7, 8, 9]
list2 = [5, 6, 'Tech', 4, 'For', 6, 'Study']
# concatenation operator +
listnew = list1 + list2
print(listnew)
Output:
[5, 6, 7, 8, 9, 5, 6, ‘Tech’, 4, ‘For’, 6, ‘Study’]
Iteration:
Iterating a list through the for-in loop.
Example:
list = ["tech", "study", "has", "the", "best", "content", "related","to", "tech"]
for i in list:
print(i)
Output:
tech
study
has
the
best
content
related
to
tech
Just like C++ Vector, java collections, python has collections(Arrays)
Collection data types:
- List
- Tuple
- Set
- Dictionary
