Catalog
1. Definition of list
1.1 Access any element in the list
1.2 modify 、 Add and remove list elements
2. Organization list
3. Index error
4. Operation list
4.1 Traverse the list
4.2 List of values
4.3 Use some elements of the list
4.4 Tuples
It consists of a series of elements sorted in a specific order , stay python Use in [ ] To express , And use commas to separate elements .
eg：pets = ['cat','pig','tiger']
Just tell me the position or index of the element Python, Take the example above , Want to print out pig and tiger：
pets = ['cat','pig','tiger']
print(pets[1])
print(pets[2]）The first position of the index of the list is 0, The last element can be -1, It can also be a number that is counting the past
pets = ['cat','pig','tiger']
pets[0] = 'monkey' // Modify the first element
pets.append('bird') // Add elements to the end of the list , Use append
pets.insert(0,'Bus') // Insert element to start , Use insert
del pets[0] // Delete the beginning element , Use del
popped_pets = pets.pop() // Delete the element at the end
pets.remove('cat') // Delete elements... Based on values , Method remove() Delete only the first specified value . If the value to be deleted may appear more than once in the list , You need to use a loop to judge remarks ：del and pop The difference is that ：del Once deleted, it cannot be used , But use pop, After deletion, you can continue to use
2.1 List permanent sort
Usage method sort(), Sort alphabetically
pets = ['cat','bird','tiger']
pets.sort()
print(pets)The printed result is ：['bird','cat','tiger'], If you want to arrange in reverse alphabetical order , It's in sort() Add parameters reverse =True that will do
2.2 Temporary sort
Usage method sorted(), Sort the list temporarily
pets = ['cat','bird','tiger']
print(sorted(pets))
print(pets)The printed result is ：
['bird','cat','tiger']
['cat','bird','tiger']
2.4 The list is printed backwards
Usage method reverse()
pets = ['cat','bird','tiger']
pets.reverse()
print(pets)Print out ：['tiger','bird','cat',]
2.5 Determine the length of the list
Usage method len( List name )
pets = ['cat','bird','tiger']
print(cars[3])After running, it will appear IndexError, Then when the list is empty , Use -1 Index errors also occur in the index
4.1.1 Use for loop
name = ['Winny','vivian','coras']
for name in name:
print(name)The input result is ：
4.1.2 Avoid indenting errors ：
name = ['Winny','vivian','coras']
for name in name:
print(name)here , After operation python Will report a mistake , Because it doesn't match the indentation .for The code executed on each element in the loop needs to be indented
4.2.1 Use function range（） To print a series of numbers
for value in range(1,5)
print(value)
Print out 1,2,3,4, No printing 5
4.2.2 Using functions range（） To create a list of numbers
number = list(range(1,5))
print (number)The input result is [1,2,3,4]
4.2.3 Using functions range（） Specify the step size
If you want to print 1-10 Previous even . be range(2,11,2), For from 2 Starting number , And then keep adding 2, Until the final value is reached or exceeded 11
4.2.4 Find the largest number in the list 、 The sum of the minimum and the sum
min（list_name）、max（list_name）、sum（list_name）
4.2.5 List of analytical
# Print 1-5 Squared to the list
square = [value*value for value in range(1,6)]4.3.1 section , And range The function is the same ,Python Stop after reaching the element before the second index you specify
name = ['Winny','kekey','coco','jos']
print(name[0:2])The result of output and is ['Winny','kekey']
If the first index is not specified , Start from the list header ,print(name[:3]) -- The output 0,1,2 The value of the index
Empathy , No last index specified , Print to the end of the list
Print the last three elements ：print(name[-3:])
4.3.2 Traversing slices , Then use for loop
4.3.3 Copy list , The method is to omit both the starting index and the ending index （[:]）
name = ['Winny','kekey','coco','jos']
other_name = [:]4.4.1 Definition of tuple ：python A value that cannot be modified is called immutable , An immutable list is called a tuple , but Use parentheses （） Instead of square brackets to identify .
numbers =(0,10)
print(numbers[0])
print(numbers[1])Results output ：0 10
4.4.2 Traverse all values , Use for
4.4.3 Change tuple variable
dimensions =(200,50)
dimensions=(100,30)
be dimensions The value of the tuple is reassigned
4.4.4 Format the code
Use four spaces for each level of indentation 、 No more than is recommended per line 80 word （ stay Settings Inside code style Set up hard ware at Value ）
The learning content of this article comes from 《Python Programming ： From introduction to practice 》
關於Python使用to_excel報錯：PermissionError: [Errno 13] Permission denied: ‘data_topic.xlsx‘
檢查了很久，最後發現是由於文件data_topic.xlsx
[note] June 20, 2022: three artifacts of Python data analysis: numpy, pandas and Matplotlib
0. Introduce cases RIGHT Examp
