In Python, arrays are created using the list
data type. A list is a collection of items that are ordered and changeable. Lists are written with square brackets and the items are separated by commas.
Here is an example of a list in Python:
my_list = [1, 2, 3, 4]
You can access the items on a list using the index number of the item in the list. The index numbers start at 0 for the first item.
# Access the first item in the list
first_item = my_list[0]
print(first_item) # Output: 1
# Access the third item in the list
third_item = my_list[2]
print(third_item) # Output: 3
You can also use negative index numbers to access items from the end of the list. For example, the index number -1 refers to the last item in the list, -2 refers to the second last item, and so on.
# Access the last item in the list
last_item = my_list[-1]
print(last_item) # Output: 4
# Access the second last item in the list
second_last_item = my_list[-2]
print(second_last_item) # Output: 3
You can also use index numbers to modify the value of an item in a list.
# Modify the value of the first item in the list
my_list[0] = 10
print(my_list) # Output: [10, 2, 3, 4]
You can use the len()
function to find the length of a list.
# Find the length of the list
list_length = len(my_list)
print(list_length) # Output: 4
You can use the append()
method to add a new item to the end of a list.
# Add a new item to the end of the list
my_list.append(5)
print(my_list) # Output: [10, 2, 3, 4, 5]
You can use the insert()
method to add a new item at a specific index in the list.
# Add a new item at index 1
my_list.insert(1, 0)
print(my_list) # Output: [10, 0, 2, 3, 4, 5]
You can use the remove()
method to remove an item from the list.
# Remove the item at index 2
my_list.remove(2)
print(my_list) # Output: [10, 0, 3, 4, 5]
You can use the pop()
method to remove and return the last item from the list.
# Remove and return the last item from the list
last_item = my_list.pop()
print(last_item) # Output: 5
print(my_list) # Output: [10, 0, 3, 4]
You can use the clear()
method to remove all items from the list.
# Remove all items from the list
my_list.clear()
print(my_list) # Output: []
You can use the index()
method to find the index of an item in the list.
my_list = [10, 3, 4]
# Find the index of the item 4
index_of_item_4 = my_list.index(4)
print(index_of_item_4) # Output: 2
You can use the count()
method to count the number of occurrences of an item in the list.
# Count the number of occurrences of the item 10
count_of_item_10 = my_list.count(10)
print(count_of_item_10) # Output: 1
You can use the sort()
method to sort the items of the list in ascending order.
my_list = [10, 3, 4, 5, 1]
# Sort the list in ascending order
my_list.sort()
print(my_list) # Output: [1, 3, 4, 5, 10]
You can also use the reverse()
method to reverse the order of the items in the list.
# Reverse the order of the items in the list
my_list.reverse()
print(my_list) # Output: [10, 5, 4, 3, 1]
Table of array methods in Python
Method | Description |
append() | Add an item to the end of the list |
clear() | Remove all items from the list |
copy() | Return a copy of the list |
count() | Return the number of occurrences of an item in the list |
extend() | Add all items from an iterable to the end of the list |
index() | Return the index of the first occurrence of an item in the list |
insert() | Insert an item at a specific index in the list |
pop() | Remove and return the item at a specific index in the list (default is the last item) |
remove() | Remove the first occurrence of an item from the list |
reverse() | Reverse the order of the items in the list |
sort() | Sort the items of the list in ascending order |
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