12 Python 3

发布时间：2023-04-15 14:15:07 所属栏目：教程来源：

导读：A tuple is a sequence of immutable Python objects. Tuples are sequences, just like lists. The main d

A tuple is a sequence of immutable Python objects. Tuples are sequences, just like lists. The ma

A tuple is a sequence of immutable Python objects. Tuples are sequences, just like lists. The main d

A tuple is a sequence of immutable Python objects. Tuples are sequences, just like lists. The main difference between the tuples and the lists is that the tuples cannot be changed unlike lists. 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.

Accessing Values in Tuples
To access values in tuple, use the square brackets for slicing along with the index or indices to obtain the value available at that index. For example −

Live Demo

#!/usr/bin/python3

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 the existing tuples to create new tuples as the following example demonstrates −

Live Demo

#!/usr/bin/python3

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/python3

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

print (tup)
del tup;
print ("After deleting tup : ")
print (tup)
This produces the following result.

Note − An exception is 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

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