Python tuple

Python’s tuples are similar to lists, except that the elements of the tuple cannot be modified.

Use parentheses for tuples and square brackets for lists.

Tuple creation is very simple, just add elements in brackets and separate them with commas.

The following examples:

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

Create an empty tuple

tup1 = ();

When the tuple contains only one element, you need to add a comma after the element

tup1 = (50,);

tuple Similar to strings, the subscript index starts from 0 and can be intercepted, combined, etc.

Accessing tuples

Tuples can use subscript indexes to access the values in the tuple, as shown in the following 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]

Output results of the above example:

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

Modify tuple

The element values in the tuple are not allowed to be modified, but we can connect and combine the tuples, as shown in the following example:

#!/usr/bin/python
# -*- coding: UTF-8 -*-

tup1 = (12, 34.56);
tup2 = ('abc', 'xyz');

and above Example output result:

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

Delete tuple

in tuple The element value of is not allowed to be deleted, but we can use the del statement to delete the entire tuple, as shown in the following example:

#!/usr/bin/python

tup = ( 'physics', 'chemistry', 1997, 2000);

print tup;
del tup;
print "After deleting tup : "
print tup;

After the above instance tuple is deleted, the output variable will have exception information, and the output is as follows:

('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

Tuple operator

Like strings, tuples can be operated using the + and * signs. This means that they can be combined and copied, resulting in a new tuple.

Python expression	Result	Description
len((1, 2 , 3))	3	Calculate the number of elements
(1, 2, 3) + (4, 5, 6)	(1, 2, 3, 4, 5, 6)	Connection
['Hi!'] * 4	['Hi!', 'Hi!', 'Hi!', 'Hi!']	Copy
3 in (1, 2, 3)	True	Whether the element exists
for x in (1, 2, 3): print x,	1 2 3	Iteration

Tuple index, interception

Because the tuple is also a sequence, we can access the tuple The element at the specified position can also intercept a section of elements in the index, as shown below:

Tuple:

L = ('spam', 'Spam', 'SPAM !')

##Python expressionResultDescription## L[2]L[-2]L[1:]

No closing delimiter

Any unsigned object, separated by commas, defaults to a tuple, as shown in the following example:

#!/usr/bin /python

print 'abc', -4.24e93, 18+6.6j, 'xyz';
x, y = 1, 2;
print "Value of x , y : ", x,y;

The above example operation result:

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

Tuple built-in functions

Python tuple contains the following built-in functions


'SPAM!'	Read the third element
' Spam'	Read in reverse; read the penultimate element
('Spam', 'SPAM !')	Intercept element

Serial number	Method and description
1	cmp(tuple1, tuple2) Compare two tuple elements.
2	len(tuple) Calculate the number of tuple elements.
3	max(tuple) Returns the maximum value of the element in the tuple.
4	min(tuple) Returns the minimum value of the element in the tuple.
5	tuple(seq) Convert the list to a tuple.