Tuples and Sequences

 None

None

is an object which is a datatype of its own (NoneType).

Used to define no value or nothing.

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var = None

print(var)

print(type(var))

PYTHON

Output

None

<class 'NoneType'>

Function Without Return

Functions assigned to a variable, when function does not have a

return

statement, the variable will get the value

None

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def increment(a):

a += 1

a = 55

result = increment(a)

print(result)

PYTHON

Output

None

Function That Returns Nothing

When a function returns no value, the default value will be

None

Example - 1

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def increment(a):

a += 1

return

a = 55

result = increment(a)

print(result)

PYTHON

Output

None

Example - 2

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def increment(a):

a += 1

return None

a = 5

result = increment(a)

print(result)

PYTHON

Output

None

Example - 3

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result = print("Hi")

print(result)

PYTHON

Output

Hi

None

Tuple

• Holds an ordered sequence of items.
• Tuple is immutable object, where as list is a mutable object.

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a = 2

tuple_a = (5, "Six", a, 8.2)

PYTHON

Creating a Tuple

• Created by enclosing elements within (round) brackets.
• Each item is separated by a comma.

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a = 2

tuple_a = (5, "Six", a, 8.2)

print(type(tuple_a))

print(tuple_a)

PYTHON

Output

<class 'tuple'>

(5, 'Six', 2, 8.2)

Tuple with a Single Item

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a = (1,)

print(type(a))

print(a)

PYTHON

Output

<class 'tuple'>

(1,)

Accessing Tuple Elements

Accessing Tuple elements is also similar to string and list accessing and slicing.

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a = 2

tuple_a = (5, "Six", a, 8.2)

print(tuple_a[1])

PYTHON

Output

Six

Tuples are Immutable

Tuples does not support modification.

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tuple_a = (1, 2, 3, 5)

tuple_a[3] = 4

print(tuple_a)

PYTHON

Output

TypeError: 'tuple' object does not support item assignment

Operations can be done on Tuples

• len()
• Iterating
• Slicing
• Extended Slicing

Converting to Tuple

tuple(sequence)

Takes a sequence and converts it into tuple.

String to Tuple

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color = "Red"

tuple_a = tuple(color)

print(tuple_a)

PYTHON

Output

('R', 'e', 'd')

List to Tuple

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list_a = [1, 2, 3]

tuple_a = tuple(list_a)

print(tuple_a)

PYTHON

Output

(1, 2, 3)

Sequence to Tuple

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tuple_a = tuple(range(4))

print(tuple_a)

PYTHON

Output

(0, 1, 2, 3)

Membership Check

Check if given data element is part of a sequence or not.

Membership Operators

• in
• not in

Example - 1

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tuple_a = (1, 2, 3, 4)

is_part = 5 in tuple_a

print(is_part)

PYTHON

Output

False

Example - 2

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tuple_a = (1, 2, 3, 4)

is_part = 1 not in tuple_a

print(is_part)

PYTHON

Output

False

List Membership

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list_a = [1, 2, 3, 4]

is_part = 1 in list_a

print(is_part)

PYTHON

Output

True

String Membership

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word = 'Python'

is_part = 'th' in word

print(is_part)

PYTHON

Output

True

Packing & Unpacking

Unpacking

Values of any sequence can be directly assigned to variables.

Number of variables in the left should match the length of sequence.

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tuple_a = ('R', 'e', 'd')

(s_1, s_2, s_3) = tuple_a

print(s_1)

print(s_2)

print(s_3)

PYTHON

Output

R

e

d

Errors in Unpacking

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tuple_a = ('R', 'e', 'd')

s_1, s_2 = tuple_a

print(s_1)

print(s_2)

PYTHON

Output

ValueError: too many values to unpack (expected 2)

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tuple_a = ('R', 'e', 'd')

s_1, s_2, s_3, s_4 = tuple_a

print(s_1)

PYTHON

Output

ValueError: not enough values to unpack (expected 4, got 3)

Tuple Packing

()

brackets are optional while creating tuples.

In Tuple Packing, Values separated by commas will be packed into a tuple.

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a = 1, 2, 3

print(type(a))

print(a)

PYTHON

Output

<class 'tuple'>

(1, 2, 3)

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a = 1,

print(type(a))

print(a)

PYTHON

Output

<class 'tuple'>

(1,)

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a, = 1,

print(type(a))

print(a)

PYTHON

Output

<class 'int'>

1