Python Tuples

A tuple is a series of immutable Python objects. Tuples are sequences, similar to lists. The c basic differences between tuples and lists are, the tuples cannot be changed unlike lists and tuples use parentheses, while lists use square brackets.

Generating a tuple is as simple as putting various comma-separated values. you can also put these comma-separated values between parentheses also. For instance −

tup1 = ('physics', 'chemistry', 1997, 2000);
tup2 = (1, 2, 3, 4, 5 );
tup3 = "a", "b", "c", "d";

The empty tuple is written as two parentheses consisting nothing −

tup1 = ();

To write a tuple consisting of a single value it is important to include a comma, even though there is only one value −

tup1 = (50,);

Similar to string indices, tuple indices begin at 0, and they can be sliced, concatenated, and so on.

Accessing Values in Tuples

To access values in a tuple, use the square brackets for slicing together with the index or indices to get value available at that index. For instance −

#!/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 generates the following result −

tup1[0]:  physics
tup2[1:5]:  [2, 3, 4, 5]

Updating Tuples

Tuples are immutable. It defines that it is not possible to update or change the values of tuple elements. You are capable to take portions of existing tuples to generate new tuples as the following illustrations demonstrate −

#!/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 generates the following result −

(12, 34.56, 'abc', 'xyz')

Delete Tuple Elements

 It is not possible to remove individual tuple elements. Of course, There is nothing wrong with putting together another tuple with the undesired elements discarded.

An entire tuple can be removed with the help of del statement. For instance −

#!/usr/bin/python

tup = ('physics', 'chemistry', 1997, 2000);
print tup;
del tup;
print "After deleting tup : ";
print tup;

This generates the following result. Note an exception raised, this is because after del tup tuple does not exist anymore −

#!/usr/bin/python

tup = ('physics', 'chemistry', 1997, 2000);
print tup;
del tup;
print "After deleting tup : ";
print tup;

Basic Tuples Operations

Tuples answer to the + and * operators similar to strings; they explain concatenation and repetition here too, except that the result is a new tuple, not a string.

In fact, tuples respond to all of the basic sequence operations we used on strings in the previous 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 for tuples work as same as they do for strings. Consider the following input −

L = ('spam', 'Spam', 'SPAM!')
Python Expression Results Explanation
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 several objects, comma-separated, written without recognizing symbols such as brackets for lists, parentheses for tuples, etc., default to tuples, as represented in these short illustrations −

#!/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 generates the following result −

abc -4.24e+93 (18+6.6j) xyz
Value of x , y : 1 2

Built-in Tuple Functions:

Python involves various tuple functions described as follows −

Sr.No. Function with Explanation
1 cmp(tuple1, tuple2)

Compares elements of both tuples.

2 len(tuple)

Provides the total length of the tuple.

3 max(tuple)

Returns item from the tuple with max value.

4 min(tuple)

Returns item from the tuple with min value.

5 tuple(seq)

Converts a list into the tuple