Python List (Iterate, append, reverse, pop, etc)

A list is an ordered set of objects in Python.

a = [1, 2, 3]

Iterate

a = ['com', 'org', 'net']

for i in a:
    print(i)

# com
# org
# net

Get element by index

a = ['com', 'org', 'net']

print(a[0])  # com
print(a[1])  # org
print(a[2])  # net

The index of the first element is 0.

Append

a = [1, 2, 3]

a.append(7)

print(a)  # [1, 2, 3, 7]

Addition

x = [1, 2]
y = [5, 6, 7]
z = x + y

print(z)  # [1, 2, 5, 6, 7]

Reverse

a = [1, 2, 3]

a.reverse()

print(a)  # [3, 2, 1]

Reverse method reverses an order.

Remove from index

a = ['com', 'org', 'net', 'gov']

a.pop(1)

print(a)  # ['com', 'net', 'gov']

Or use built-in function del.

a = ['com', 'org', 'net', 'gov']

del a[2]

print(a)  # ['com', 'org', 'gov']

Extend

x = [1, 2]
y = [5, 6, 7]
x.extend(y)

print(x)  # [1, 2, 5, 6, 7]

The extend and append are confusing. The extend gets all the items from the argument list and appends those to the list. But append simply appends the argument as an item.

x1 = [1, 2]
x2 = [1, 2]
y = [5, 6, 7]

x1.extend(y)
x2.append(y)

print(x1)  # [1, 2, 5, 6, 7]
print(x2)  # [1, 2, [5, 6, 7]]