1, part of the elements of the processing list is called a slice, create a slice, you can specify the first element to be used and the index of the last element.
2. This lets Python create a slice that starts at the first element and ends at the last, i.e., copy the entire list.
an actual example
names = ['zhang_san','chen_cheng','li_hong','liu_li','chen_yu'] print(names[0:3]) print(names[0:-1]) print(names[:]) print(names[-1]) print(names[-3:]) Negative indexing returns the element at the corresponding distance from the end of the list,To export the last three players on the list，Slices can be usednames[-3:] function (math.)range()equal to， PythonStops after reaching the element preceding the second index you specify ['zhang_san', 'chen_cheng', 'li_hong'] ['zhang_san', 'chen_cheng', 'li_hong', 'liu_li'] ['zhang_san', 'chen_cheng', 'li_hong', 'liu_li', 'chen_yu'] chen_yu ['li_hong', 'liu_li', 'chen_yu']
Instance Extension:
A list is similar to an array in java, with square brackets and commas separating the elements.
#Assign, print children_names = ['Du Ziteng','Du Xiaoyue','Du Xiaoxing','Du Xiaoyang','Du Xiaohua'] print(children_names)
Run results:
['Du Ziteng', 'Du Xiaoyue', 'Du Xiaoxing', 'Du Xiaoyang', 'Du Xiaohua']
Access to one of the elements
children_names = ['Du Ziteng','Du Xiaoyue','Du Xiaoxing','Du Xiaoyang','Du Xiaohua'] print(children_names[2]) # Print one of the elements by index, starting at 0 print(children_names[-1]) # Print the last element, by index, and so on -1,-2,-3... print(len(children_names)) # Get the length of the list
Run results:
Du Xiaoxing (1905-1992), Mao *'s second wife
Dulcimer (Harry Potter)
5
Modifying elements
children_names = ['Du Ziteng','Du Xiaoyue','Du Xiaoxing','Du Xiaoyang','Du Xiaohua'] children_names[2]='Du Xiaolao' # Follow the index and directly override the assignment print(children_names)
Run results:
['Du Ziteng', 'Du Xiaoyue', 'Du Xiaolao', 'Du Xiaoyang', 'Du Xiaohua']
Adding Elements
children_names = ['Du Ziteng','Du Xiaoyue','Du Xiaoxing','Du Xiaoyang','Du Xiaohua']
children_names.append("Du Xiaolai 2.") #Append to the end of the list
children_names.insert(0,"Du Xiaodu.") # Insert elements according to index position
print(children_names)
Run results:
['Du Xiaodu', 'Du Ziteng', 'Du Xiaoyue', 'Du Xiaoxing', 'Du Xiaoyang', 'Du Xiaohua', 'Du Xiaolao 2']
Delete element
- The difference between the use of del and pop is that after deletion it is used or not [based on the index].
- Delete by value, remove
del children_names[0] # Delete elements completely, by index
children_pop = children_names.pop()
# To be precise, pop up the tail element of the list [you can also specify the index], assign it to a variable, and save it temporarily
children_names.remove("Du Xiaolai 2.") # If there are duplicates, only the first one will be deleted.
Sorting the list
- Use sort to sort permanently in alphabetical order
- Temporarily sort the list in alphabetical order using sorted
- Print the list backwards
visitors = ['a1','b1','c1','d1','e'] () # Alphabetical, sorted, irreversible # (reverse=True) # In reverse alphabetical order, irreversible print(sorted(visitors)) # Temporary sorting without affecting the existing data order print(sorted(visitors,reverse=True)) # Temporary reverse sorting without affecting the existing data order () # Directly inverted, not related to alphabetical order, reversible, just do it again #
Running results:
['a1', 'b1', 'c1', 'd1', 'e']
['e', 'd1', 'c1', 'b1', 'a1']
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