Variable - List

Lists are used to store multiple items in a single variable.

List items are ordered, changeable, and allow duplicate values.

Similarly to Array, list items are indexed, the first item has index [0], the second item has index [1] etc.

When we say that lists are ordered, it means that the items have a defined order, and that order will not change.

If you add new items to a list, the new items will be placed at the end of the list.

The list is changeable, meaning that we can change, add, and remove items in a list after it has been created.

Use square brackets [ ]

#Example 1

list1 = ['Alia', 'Yusof', 23, 24]
list2 = ["apple", "cherry", "orange"]
list3 = [1, 2, 3, 4, 5]
thislist = ["apple", "banana", "cherry", "apple", "cherry"]

Accessing Item in List

Exercise #1: Creating List

list1 = ["apple", "grape", "orange", "banana", "strawberry"]

print (list1)

Output: ['apple', 'grape', 'orange', 'banana', 'strawberry']

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Exercise #2: Indexing

print (list1[0]) #return item with index 0
print (list1[1]) #return item with index 1
print (list1[3]) #return item with index 3

Output: apple grape banana

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Exercise #3: Slicing and Range Indexing

print (list1[:0]) #first 0 item start with index 0
print (list1[:2]) #first 2 items start with index 0
print (list1[2:4]) #first 4 items but skip 2 items

Output: [] ['apple', 'grape'] ['orange', 'banana']

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Exercise #4: Last Item

print (list1[-1]) #return last item
print (list1[-2]) #return second last item
print (list1[-2:]) #return 2 last items

Output:

strawberry banana ['banana', 'strawberry']

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Exercise #5: Change Item Value

list1[2] = "guava" #change item at index 2
print (list1)

Output: ['apple', 'grape', 'guava', 'banana', 'strawberry']

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Exercise #6: Delete Item Value

del list1[2] #delete item at index 2
print (list1)

Output:

['apple', 'grape', 'banana', 'strawberry']

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Exercise #7: Add Item Value

list1.append('pineapple') #add item at the end of list
print (list1)

list1.insert(1, 'mango') #insert new item at index 1
print (list1)

Output:

['apple', 'grape', 'banana', 'strawberry', 'pineapple'] ['apple', 'mango', 'grape', 'banana', 'strawberry', 'pineapple']

List Methods

Method	Description
append()	Adds an element at the end of the list
clear()	Removes all the elements from the list
copy()	Returns a copy of the list
count()	Returns the number of elements with the specified value
extend()	Add the elements of a list (or any iterable), to the end of the current list
index()	Returns the index of the first element with the specified value
insert()	Adds an element at the specified position
pop()	Removes the element at the specified position
remove()	Removes the item with the specified value
reverse()	Reverses the order of the list
sort()	Sorts the list