Py09: Tuple

Table of Content

1. Introduction
2. Accessing Tuple
3. Slicing
4. Membership

A sequence of data stored as a single unit. A tuple is generally faster than a list, and immutable.

Introduction

A Tuple is a list and has almost the same function to retrieve its data. Tuple cannot add a new element or remove elements from it. A tuple is defined using parentheses ().

tuple_name = ()
tuple_name = (item1, item2, ...., itemN)

the parentheses can be omitted, but it's encouraged to use them. Its item can be an integer, float, string, or even a list. a tuple can consist of different data type items.

a_tuple = (1, 3.5, "James")

print(a_tuple) # prints the items in tuple

Output

(1, 3.5, 'James')
>

Writing code the following way does not create a tuple.

a_tuple = ("James")

print(type(a_tuple)) # returns the data type 

print(a_tuple)       # prints the data 

Output

<class 'str'>
James
>

to create a tuple that only has one item, a comma is needed after the first item and optionally the parentheses can be omitted.

a_tuple = ("James",)

print(type(a_tuple)) # returns the data type

print(a_tuple)       # prints the items in tuple

Output

<class 'tuple'>
('James',)
>

A tuple can be deleted by using the del operation as shown in the following syntax:

del tuple_name

Accessing Tuple

A tuple element is accessed using the index number specified in the square bracket as shown below:

tupple_name[index]

For example, to get the number 7 in the tuple, use index value 2.

a_tuple = (4, 5, 7, 3)

print(a_tuple[2])        # 7 is 3rd item, so index 2

Output

7
>

using a negative index, -1 for the last element, -2 for the second last and etc.

a_tuple = (4, 5, 7, 3)

print(a_tuple[-1])       # last item is 3

Output

3
>

to access a nested list or tuple, we need two indexes.

a_tuple = (4, 5, 7, [2, 6])

print(a_tuple[3][0])      # 1st item inside 4th item

Output

2
>

The count() function to count how many times an element appears inside a tuple. For example, the letter 'e' appears 3 times in the following tuple.

a_tuple = ('t','e','a','c','h','e','r','c','u','b','e')

print(a_tuple.count('e')) # 'e' appeard 3 times

Output

3
>

The index() function returns the index number of the element in a tuple. For example, the index of the letter 'r' is 6:

a_tuple = ('t','e','a','c','h','e','r','c','u','b','e')

print(a_tuple.index('r')) # the index of 'r' is 6

Output

6
>

Slicing

To retrieve a subset of the tuple. Syntax is:

tuple_name[start: end]

return element from the start index to the end-1 index. The default value for the start is 0 (zero) and for the end is the length of a tuple.

a_tuple = ('red', 'green', 'blue','grey')

print(a_tuple[1:3]) # get 2nd until 3rd item

print(a_tuple[:])   # get 1st until last item

Output

('green', 'blue')
('red', 'green', 'blue', 'grey')
>

Membership

To check if an element exists inside a tuple. This statement will return True if exists, and False if not.

value [in|not in] tuple_name

This example checks if a string exists in a tuple

a_tuple = ("Math", "Science", "Geography", "History")

print("Math" in a_tuple)           # True
print("Chemistry" in a_tuple)      # False

Output

True
False
>

This membership check is used together with for loop to iterate through the tuple. The following, example displays all the elements in the tuple:

a_tuple = ("Math", "Science", "Geography", "History")

for element in a_tuple:
    print(element)

Output

Math
Science
Geography
History
> 

A post by Cuber