Python in tuple Use
One 、 What is a tuple ？
An ordered list is called a tuple ：tuple.tuple and list Very similar , however tuple Once initialized, it cannot be modified .
Two 、 usage
1. tuple Definition of tuple
Python A tuple of is similar to a list , The difference is that the elements of a tuple cannot be modified . Tuples use braces , Use square brackets for lists . Tuples are easy to create , You just need to add elements in parentheses , And separate them with commas . Examples are as follows ：
tup1 = ('361way', 'com', 1997, 2000)
print(type(tup1))
tup2 = (1, 2, 3, 4, 5)
tup3 = "a", "b", "c", "d"
print(type(tup3))
Through here tup3 It can be seen that , It's not bracketed, including , But it's also a tuple . So remember ： Any unsigned object , Separated by commas , Default to tuple . In addition, special attention should be paid to the creation of tuples when there is only one element ：
tup1 = (111)
print(type(tup1))
tup1 = ("abc")
print(type(tup1))
tup1 = ("abc",)
print(type(tup1))
When a tuple contains only one element , You need to add a comma after the element , Otherwise it would be int or string And other data types . If you just create an empty tuple , It's not affected by commas ：
tup1 = ()
print(type(tup1))
2. Index and slice of tuples
With the string 、 The list type is the same , Tuples also support indexing and slicing . And the usage is the same ,
Let's take a look at ：
tup1 = ('361way', 'com', 2013, 2014)
print(tup1[0])
print(tup1[4]) # An error occurred when the value exceeds its index range
tup2 = (1, 2, 3, 4, 5, 6, 7)
print(tup2[1:5])
From the above results we can see that , When extracting the data of a single element of a tuple , What you get is the original type of the data ; When you take out one of the element values, you still get tuples .
3. Modify the value of the tuple
Element values in tuples are not allowed to be deleted , But you can use del Statement to delete the entire tuple , The following example :
tup1 = ('361way', 'com', 2013, 2014)
del tup1[3] # Delete single element , Report errors
tup1[3] = 'abc' # Change the value of an element , Report errors
print(tup1[3])
del tup1 # Delete the entire tuple , normal
print(tup1)
in application , There are times when you need to modify the value of a tuple , Then what shall I do? ？ It can be achieved in a flexible way .
Examples are as follows ：
tup1 = ('361way', 'com', 2013, 2014)
list1 = list(tup1)
print(list1)
list1[3] = 'change'
print(list1)
tup1 = tuple(list1)
print(tup1)
Can be tuple The value of the tuple is passed first by list Convert to list , Then modify the values in the list , It is amended as follows list Turn into tuple .
But what we need to pay attention to here is tup1 It's not that tup1, The details can be obtained through id Function to view , Found that its memory address has changed .
3、 ... and 、 summary
This article is based on Python Basics , It mainly introduces Python In the foundation tuple Use of tuples , about tuple The usage of "is explained in detail , With a wealth of cases , The display of the code effect diagram helps you to better understand .
tuple yes Python Built in ordered collection , A variable , One is immutable . Choose to use them as needed .
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Want to learn more Python Web crawler and data mining knowledge , Go to a professional website ：http://pdcfighting.com/
