1. What is a list?
A list is a data structure for an ordered set of items. After creating a list, users can access, modify, add or delete items in the list, that is, lists are mutable data types.
Second, the creation of the list
1. Use square brackets
list=[] # create an empty list
list=['hello','world',98]2. Call the built-in function list()
list() # create an empty list
list(iterable) #Create a list containing the items in the enumerable object iterable
list(['hello','world',98])Third, the value of the access list
1. By subscript index
s[subscript] = x # set list elements, x is any object
2. Through for loop traversal
3. Traverse through while loop
4. Slicing operation
Part of a sequence(s) can be intercepted by slicing
The basic form of the slice operation is as follows: s[i:j] or s[i:j:k]
i is the start subscript of the sequence (including s[i]); j is the end subscript of the sequence (excluding s[j]); k is the step size. If i is omitted, start from index 0; if j is omitted, until the end of the sequence; if k is omitted, the step size is 1.
5. Determine whether the list element exists
element in listname
element not in listname
Fourth, the method of the list object
Assuming the list is named list
1. Sorting of list elements
list.reverse() # reverse
list.sort() #Sort, default ascending
list.sort（reverse = True）#降序
sorted() built-in function
2. Deletion of list elements
list.clear() #Delete all elements, equivalent to del list[:]
list.pop() # Delete according to the index, you can return the deleted value
list.remove() deletes according to the element, only the element that appears for the first time can be deleted
3. List insert element
list.append(x) # Append the object x to the end of the list
list.insert(i,x) #Insert object x at subscript i position
list.extend(t) #The sequence t is appended to the end of the list list
4. Change list elements
Modify the list elements, find the specified position and assign
5. List Comprehension Expressions
Using list comprehension expressions can simply and efficiently process an iterable object and generate a list of results. List comprehension expressions are as follows:
