Tuples are used to store multiple items in a single variable.
Tuple is one of 4 built-in data types in Python used to store collections of data, the other 3 are List, Set, and Dictionary, all with different qualities and usage.
A tuple is a collection which is ordered and unchangeable.
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.
*Set items are unchangeable, but you can remove and/or add items whenever you like. **As of Python version 3.7, dictionaries are ordered. In Python 3.6 and earlier, dictionaries are unordered.
When choosing a collection type, it is useful to understand the properties of that type. Choosing the right type for a particular data set could mean retention of meaning, and, it could mean an increase in efficiency or security.
Access Tuple Items
You can access tuple items by referring to the index number, inside squarebrackets:
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.
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")
Change Tuple Values
Once a tuple is created, you cannot change its values. Tuples are unchangeable, or immutable as it also is called.
But there is a workaround. You can convert the tuple into a list, change the list, and convert the list back into a tuple.
Convert the tuple into a list to be able to change it:
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 build-in append() method, but there are other ways to add items to a tuple.
1. 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.
Convert the tuple into a list, add "orange", and convert it back into a tuple:
2. 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)
Note: When creating a tuple with only one item, remember to include a comma after the item, otherwise it will not be identified as a tuple.
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:
Note: The number of variables must match the number of values in the tuple, if not, you must use an asterisk to collect the remaining values as a list.
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":
If the asterisk is added to another variable name than the last, Python will assign values to the variable until the number of values left matches the number of variables left.
You can loop through the tuple items by using a for loop.
Iterate through the items and print the values:
thistuple = ("apple", "banana", "cherry") for x in thistuple: print(x)
Loop Through the Index Numbers
You can also loop through the tuple items by referring to their index number. Use the range() and len() 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 list items by using a while loop. Use the len() function to determine the length of the tuple, then start at 0 and loop your way through the tuple items by refering 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
Join Two Tuples
To join two or more tuples you can use the + operator: