If you are interested to learn about the python lists
A tuple is a collection of objects which ordered and immutable. 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.Tuples are sequences, just like lists. The differences between tuples and lists are, the tuples cannot be changed unlike lists and tuples use parentheses, whereas lists use square brackets .Creating a tuple is as simple as putting different comma-separated values. Optionally you can put these comma-separated values between parentheses also. For example −
tup1 = ('physics', 'chemistry', 1997, 2000);
tup2 = (1, 2, 3, 4, 5 );
tup3 = "a", "b", "c", "d";
The empty tuple is written as two parentheses containing nothing −
tup1 = ();
To write a tuple containing a single value you have to include a comma, even though there is only one value −
tup1 = (50,);
Like string indices, tuple indices start at 0, and they can be sliced, concatenated, and so on.
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.
Ordered
When we say that tuples are ordered, it means that the items have a defined order, and that order will not change.
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:
thistuple = ("apple", "banana", "cherry", "apple", "cherry")<br>print(thistuple)
Tuple Length
To determine how many items a tuple has, use the len()
function:
Example
Print the number of items in the tuple:
thistuple = ("apple", "banana", "cherry")<br>print(len(thistuple))
Create Tuple With One Item
To create a tuple with only one item, you have to add a comma after the item, otherwise Python will not recognize it as a tuple.
Example
One item tuple, remember the comma:thistuple = (“apple”,)
print(type(thistuple))
#NOT a tuple<br>thistuple = ("apple")<br>print(type(thistuple))
Tuple Items – Data Types
Tuple items can be of any data type:
Example
String, int and boolean data types:
tuple1 = ("apple", "banana", "cherry")<br>tuple2 = (1, 5, 7, 9, 3)<br>tuple3 = (True, False, False)
A tuple can contain different data types:
Example
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’>
Example
What is the data type of a tuple?
mytuple = ("apple", "banana", "cherry")<br>print(type(mytuple))
The tuple() Constructor
It is also possible to use the tuple() constructor to make a tuple.
Example
Using the tuple() method to make a tuple:
thistuple = tuple(("apple", "banana", "cherry")) # note the double round-brackets<br>print(thistuple)
Accessing Values in Tuples
To access values in tuple, use the square brackets for slicing along with the index or indices to obtain value available at that index. For example −
#!/usr/bin/python tup1 = ('physics', 'chemistry', 1997, 2000); tup2 = (1, 2, 3, 4, 5, 6, 7 ); print "tup1[0]: ", tup1[0]; print "tup2[1:5]: ", tup2[1:5];
When the above code is executed, it produces the following result −
tup1[0]: physics tup2[1:5]: [2, 3, 4, 5]
Updating Tuples
Tuples are immutable which means you cannot update or change the values of tuple elements. You are able to take portions of existing tuples to create new tuples as the following example demonstrates −
#!/usr/bin/python tup1 = (12, 34.56); tup2 = ('abc', 'xyz'); # Following action is not valid for tuples # tup1[0] = 100; # So let's create a new tuple as follows tup3 = tup1 + tup2; print tup3;
When the above code is executed, it produces the following result −
(12, 34.56, 'abc', 'xyz')
Delete Tuple Elements
Removing individual tuple elements is not possible. There is, of course, nothing wrong with putting together another tuple with the undesired elements discarded.
To explicitly remove an entire tuple, just use the del statement. For example −
#!/usr/bin/python tup = ('physics', 'chemistry', 1997, 2000); print tup; del tup; print "After deleting tup : "; print tup;
This produces the following result. Note an exception raised, this is because after del tup tuple does not exist any more −
('physics', 'chemistry', 1997, 2000) After deleting tup : Traceback (most recent call last): File "test.py", line 9, in <module> print tup; NameError: name 'tup' is not defined
Basic Tuples Operations
Tuples respond to the + and * operators much like strings; they mean concatenation and repetition here too, except that the result is a new tuple, not a string. In fact, tuples respond to all of the general sequence operations we used on strings in the prior chapter −
Python Expression | Results | Description |
---|---|---|
len((1, 2, 3)) | 3 | Length |
(1, 2, 3) + (4, 5, 6) | (1, 2, 3, 4, 5, 6) | Concatenation |
(‘Hi!’,) * 4 | (‘Hi!’, ‘Hi!’, ‘Hi!’, ‘Hi!’) | Repetition |
3 in (1, 2, 3) | True | Membership |
for x in (1, 2, 3): print x, | 1 2 3 | Iteration |
Indexing, Slicing, and Matrixes
Because tuples are sequences, indexing and slicing work the same way for tuples as they do for strings. Assuming following input −
L = ('spam', 'Spam', 'SPAM!')
Python Expression | Results | Description |
---|---|---|
L[2] | ‘SPAM!’ | Offsets start at zero |
L[-2] | ‘Spam’ | Negative: count from the right |
L[1:] | [‘Spam’, ‘SPAM!’] | Slicing fetches sections |
No Enclosing Delimiters
Any set of multiple objects, comma-separated, written without identifying symbols, i.e., brackets for lists, parentheses for tuples, etc., default to tuples, as indicated in these short examples −
#!/usr/bin/python print 'abc', -4.24e93, 18+6.6j, 'xyz'; x, y = 1, 2; print "Value of x , y : ", x,y;
When the above code is executed, it produces the following result −
abc -4.24e+93 (18+6.6j) xyz Value of x , y : 1 2
Python – Access Tuple Items
Access Tuple Items
You can access tuple items by referring to the index number, inside square brackets:
Example
Print the second item in the tuple:
thistuple = ("apple", "banana", "cherry") print(thistuple[1])
Negative Indexing
Negative indexing means start from the end.
-1
refers to the last item, -2
refers to the second last item etc.
Example
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.
Example
Return the third, fourth, and fifth item:
thistuple = ("apple", "banana", "cherry", "orange", "kiwi", "melon", "mango") print(thistuple[2:5])
Python – Update Tuples
Tuples are unchangeable, meaning that you cannot change, add, or remove items once the tuple is created. But there are some workarounds.
Change Tuple Values
Once a tuple is created, you cannot change its values. Tuples are unchangeable But there is a workaround. You can convert the tuple into a list, change the list, and convert the list back into a tuple.
Example
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)
Python – Unpack Tuples
Unpacking a Tuple
When we create a tuple, we normally assign values to it. This is called “packing” a tuple:
Example
Packing a tuple:
fruits = ("apple", "banana", "cherry")
But, in Python, we are also allowed to extract the values back into variables. This is called “unpacking”:
Example
Unpacking a tuple:
fruits = ("apple", "banana", "cherry") (green, yellow, red) = fruits print(green) print(yellow) print(red)
Python – Loop Tuples
Loop Through a Tuple
You can loop through the tuple items by using a for
loop.
Example
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.
Example
Print all items by referring to their index number:
thistuple = ("apple", "banana", "cherry") for i in range(len(thistuple)): print(thistuple[i])