Lists in Python

 1. List

• A list is a collection that is ordered and changeable. Allows duplicate members.
• Python Lists are similar to arrays in C.
•  However, the list can contain data of different types. 
• The items stored in the list are separated with a comma (,) and enclosed within square brackets [].

 

Examples

list = ["apple", "banana", "cherry"]    #list of fruits
print(list)
 list = ["apple", "banana", "cherry", "apple", "cherry"]     #duplicate items
print(list)
 print(len(list))     #len()...length of list
list1 = ["abc", 34, True, 40, "male"]   #list of diff data types
mylist = ["apple", "banana", "cherry"]
print(type(mylist))    #type of list

2. Python - Access List Items

List items are indexed and you can access them by referring to the index number

The first item has index 0.

thislist = ["apple", "banana", "cherry"]

print(thislist[1])  

3. Negative indexing means start from the end

-1 refers to the last item, -2 refers to the second last item etc.

list = ["apple", "banana", "cherry"]

print(list[-1])

4. Range of Indexes

You can specify a range of indexes by specifying where to start and where to end the range.

thislist = ["apple", "banana", "cherry", "orange", "kiwi", "melon", "mango"]

print(thislist[2:5])

Note: The search will start at index 2 (included) and end at index 5 (not included).

5. Python - Change List Items

To change the value of a specific item, refer to the index number:

thislist = ["apple", "banana", "cherry"]

thislist[1] = "blackcurrant"

print(thislist)

thislist = ["apple", "banana", "cherry", "orange", "kiwi", "mango"]

thislist[1:3] = ["blackcurrant", "watermelon"]

print(thislist)

6. Python - Add List Items

To add an item to the end of the list, use the append() method

a = ["apple", "banana", "cherry"]

a.append("orange")

print(a)

7. Python - Remove List Items

The remove() method removes the specified item.

thislist = ["apple", "banana", "cherry"]

thislist.remove("banana")

print(thislist)

The pop() method removes the specified index.

thislist = ["apple", "banana", "cherry"]

thislist.pop(1)

print(thislist)

The del keyword also removes the specified index

thislist = ["apple", "banana", "cherry"]

del thislist[0]

print(thislist)

8. Python - Clear the List

The clear() method empties the list.

The list still remains, but it has no content.

thislist = ["apple", "banana", "cherry"]

thislist.clear()

print(thislist)