Python (Tuples)

Python Tuple:

What is Tuple?

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

thistuple = ("apple", "banana", "cherry")
print(thistuple)

Tuple Items

Tuple items are ordered, unchangeable, and allow duplicate values.

Tuple items are indexed, the first item has index [0], the second item has index [1] etc.

t = (1, 2, 3, 2))
print(t[0])   # 1
print(t[1:3]) # (2, 3)

Ordered

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

prediction = ("cat", 0.95, "image_01.jpg")

• index 0 → label
• index 1 → confidence
• index 2 → filename

label = prediction[0]
confidence = prediction[1]
file = prediction[2]

print(label, confidence, file)

Unchangeable

Tuples are unchangeable, meaning that we cannot change, add or remove items after the tuple has been created.

Allow Duplicates

Since tuples are indexed, they can have items with the same value:

Example

Tuples allow duplicate values:

tuple = ("apple", "samsung", "vivo", "apple", "samsung")
print(tuple)

Tuple Length

To determine how many items a tuple has, use the [len()](https://www.w3schools.com/python/ref_func_len.asp) function:

tuple = ("apple", "samsung", "vivo", "apple", "samsung")
print(len(tuple)) 5

Tuple Items — Data Types

Tuple items can be of any data type:

String, int and boolean data types:

tuple1 = ("apple", "banana", "cherry")
tuple2 = (1, 5, 7, 9, 3)
tuple3 = (True, False, False)

A tuple with strings, integers and boolean values:

tuple1 = ("abc", 34, True, 40, "male")

type()

From Python’s perspective, tuples are defined as objects with the data type ‘tuple’:

<class ‘tuple’>

What is the data type of a tuple?

mytuple =("abc", 34, True, 40, "male")
print(type(mytuple))

The tuple() Constructor

It is also possible to use the tuple() constructor to make a tuple. Using the tuple() method to make a tuple:

mytuple = tuple (("abc", 34, True, 40, "male"))
print(mytuple) # note the double round-brackets

Python Collections (Arrays)

There are four collection data types in the Python programming language:

• **List** is a collection which is ordered and changeable. Allows duplicate members.
• Tuple is a collection which is ordered and unchangeable. Allows duplicate members.
• **Set* is a collection which is unordered, unchangeable, and unindexed. No duplicate members.
• **Dictionary is a collection which is ordered and changeable. No duplicate members.

Python — Update Tuples

Tuples are unchangeable, meaning that you cannot change, add, or remove items once the tuple is created.

x = ("apple", "banana", "cherry")
y = list(x)
y[1] = "kiwi"
x = tuple(y)

print(x)

Add Items

Since tuples are immutable, they do not have a built-in append() method, but there are other ways to add items to a tuple.

Convert into a list: Just like the workaround for changing a tuple, you can convert it into a list, add your item(s), and convert it back into a tuple.

thistuple = ("apple", "banana", "cherry")
y = list(thistuple)
y.append("orange")
thistuple = tuple(y)

Add tuple to a tuple. You are allowed to add tuples to tuples, so if you want to add one item, (or many), create a new tuple with the item(s), and add it to the existing tuple:

Create a new tuple with the value "orange", and add that tuple:
thistuple = ("apple", "banana", "cherry")
y = ("orange",)
thistuple += y
print(thistuple)

Remove Items

Note: You cannot remove items in a tuple.

Tuples are unchangeable, so you cannot remove items from it, but you can use the same workaround as we used for changing and adding tuple items:

Convert the tuple into a list, remove “apple”, and convert it back into a tuple:

thistuple = ("apple", "banana", "cherry")
y = list(thistuple)
y.remove("apple")
thistuple = tuple(y)

Change Tuple Values

Once a tuple is created, you cannot change its values. Tuples are unchangeable, or immutable as it also is called.

Python — Access Tuple Items

Access Tuple Items

You can access tuple items by referring to the index number, inside square brackets:

tuple = ("apple", "banana", "cherry")
print(tuple[1])

Negative Indexing

Negative indexing means start from the end.-1 refers to the last item, -2 refers to the second last item etc.

Print the last item of the tuple:

thistuple = ("apple", "banana", "cherry")
print(thistuple[-1])

Range of Indexes

You can specify a range of indexes by specifying where to start and where to end the range.

When specifying a range, the return value will be a new tuple with the specified items.

Return the third, fourth, and fifth item:

thistuple = ("apple", "banana", "cherry", "orange", "kiwi", "melon", "mango")
print(thistuple[2:5]) //('cherry', 'orange', 'kiwi')

//By leaving out the start value, the range will start at the first item:
thistuple = ("apple", "banana", "cherry", "orange", "kiwi", "melon", "mango")
print(thistuple[:4]) // ('apple', 'banana', 'cherry', 'orange')

// By leaving out the end value, the range will go on to the end of the tuple:
thistuple = ("apple", "banana", "cherry", "orange", "kiwi", "melon", "mango")
print(thistuple[2:]) // ('cherry', 'orange', 'kiwi', 'melon', 'mango')

Range of Negative Indexes

Specify negative indexes if you want to start the search from the end of the tuple:

This example returns the items from index -4 (included) to index -1 (excluded)

thistuple = ("apple", "banana", "cherry", "orange", "kiwi", "melon", "mango")
print(thistuple[-4:-1]) // ('orange', 'kiwi', 'melon')

Check if Item Exists

To determine if a specified item is present in a tuple use the in keyword:

Check if “apple” is present in the tuple:

thistuple = ("apple", "banana", "cherry")
if "apple" in thistuple:
 print("Yes, 'apple' is in the fruits tuple")
output:​
Yes, 'apple' is in the fruits tuple

Unpacking a Tuple

When we create a tuple, we normally assign values to it. This is called “packing” a tuple:

fruits = ("apple", "banana", "cherry")

we are also allowed to extract the values back into variables. This is called “unpacking”:

fruits = ("apple", "banana", "cherry")
(green, yellow, red) = fruits
print(green)
print(yellow)
print(red)

Using Asterisk*

If the number of variables is less than the number of values, you can add an * to the variable name and the values will be assigned to the variable as a list:

Assign the rest of the values as a list called "red":

fruits = ("apple", "banana", "cherry", "strawberry", "raspberry")
(green, yellow, *red) = fruits
print(green)
print(yellow)
print(red)

Python — Join Tuples

Join Two Tuples

To join two or more tuples you can use the + operator: Join two tuples:

tuple1 = ("a", "b" , "c")
tuple2 = (1, 2, 3)
tuple3 = tuple1 + tuple2
print(tuple3)

Multiply Tuples

If you want to multiply the content of a tuple a given number of times, you can use the * operator: Multiply the fruits tuple by 2:

fruits = ("apple", "banana", "cherry")
mytuple = fruits * 2
print(mytuple)

Python — Loop Tuples

Loop Through a Tuple

You can loop through the tuple items by using a [for](https://www.w3schools.com/python/ref_keyword_for.asp) loop.

thistuple = ("apple", "banana", "cherry")
for x in thistuple:
 print(x) 

//apple
//banana
//cherry

Loop Through the Index Numbers

You can also loop through the tuple items by referring to their index number.

Use the [range()](https://www.w3schools.com/python/ref_func_range.asp) and [len()](https://www.w3schools.com/python/ref_func_len.asp) functions to create a suitable iterable.

Print all items by referring to their index number:

thistuple = ("apple", "banana", "cherry")
for i in range(len(thistuple)):
 print(thistuple[i])

Using a While Loop

You can loop through the tuple items by using a [while](https://www.w3schools.com/python/ref_keyword_while.asp) loop.

Use the [len()](https://www.w3schools.com/python/ref_func_len.asp) function to determine the length of the tuple, then start at 0 and loop your way through the tuple items by referring to their indexes.

Remember to increase the index by 1 after each iteration.

Print all items, using a while loop to go through all the index numbers:

thistuple = ("apple", "banana", "cherry")
i = 0
while i < len(thistuple):
 print(thistuple[i])
 i = i + 1

Python Tuple Methods

Python has two built-in methods that you can use on tuples.

count() - Returns the number of times a specified value occurs in a tuple index() - Searches the tuple for a specified value and returns the position of where it was found. Example for usage

Count & Index

t = (1, 2, 3, 2, 2, 4)

print(t.count(2))

//Strings

fruits = ("apple", "banana", "apple", "cherry")

print(fruits.count("apple"))

labels = ("cat", "dog", "cat", "cat", "dog")

print(labels.count("cat"))

fruits = ("apple", "banana", "cherry")
print(fruits.index("cherry"))

t = (10, 20, 30, 20)

print(t.index(20))

t = (1, 2, 3)
if 5 in t:
 print(t.index(5))
else:
 print("Not found")