Python Learning (7) about list operations related commands and shallow copy deep copy

In Python, [] represents a list. The list has various operations commands.

1, append () method, add an element to the tail of the list.

Note the append () method differs from the Extend () method: List.append (object) Adds an object to the list objects and list.extend (sequence) adds the contents of a sequence SEQ to the list

For example:

1names=["Hongtao","Xiaoweihong","Hongyuchan",["show530","Luby"],"Hongpingshui","Guochaoxi"]2names2=["Liuyi","Zhangsong"]3 4 names.extend (names2)5 Print(names)6 7>>>>>>>8['Hongtao','Xiaoweihong','Hongyuchan', ['show530','Luby'],'Hongpingshui','Guochaoxi','Liuyi','Zhangsong']9 ___________________________________________________Ten  Onenames=["Hongtao","Xiaoweihong","Hongyuchan",["show530","Luby"],"Hongpingshui","Guochaoxi"] Anames2=["Liuyi","Zhangsong"] -  - names.append (names2) the Print(names) -  ->>>>>>>>> -['Hongtao','Xiaoweihong','Hongyuchan', ['show530','Luby'],'Hongpingshui','Guochaoxi', ['Liuyi','Zhangsong']]

2. About the same and different points of remove (), pop (), and Del List operations:

(1) Remove is the first element that matches the condition. Does not delete a specific index.

1 >>> a = [0, 2, 2, 3]

2 >>> a.remove (2)

3 >>> a

4 [0, 2, 3]

(2) For Del, it is deleted based on the index (where the element is located).

1 >>> a = [3, 2, 2, 1]

2 >>> del a[1]

3 [3, 2, 1]

(3) The pop return is the value you pop up.

1 >>> a = [4, 3, 5]

2 >>> a.pop (1)

3 3

4 >>> a

5 [4, 5]

3. About the difference between deep copy and shallow copy:

In short, depth copy is simply a copy of a list, just like a list. When a shallow copy of copy encounters a list containing a list, he only replicates the memory address.

For example, the following code:

1 ImportCopy2names=["Hongtao","Xiaoweihong","Hongyuchan",["show530","Luby"],"Hongpingshui","Guochaoxi"]3Names2=copy.copy (names)4names[3][0]="SHOW530"5names[3][1]="Luby"6 Print(Names2)7 8Output Results >>>>>>>9 Ten['Hongtao','Xiaoweihong','Hongyuchan', ['SHOW530','Luby'],'Hongpingshui','Guochaoxi'] One  A  - ImportCopy -names=["Hongtao","Xiaoweihong","Hongyuchan",["show530","Luby"],"Hongpingshui","Guochaoxi"] theNames2=copy.deepcopy (names) -names[3][0]="SHOW530" -names[3][1]="Luby" - Print(Names2) +  -Output Results >>>>>>> +  A['Hongtao','Xiaoweihong','Hongyuchan', ['show530','Luby'],'Hongpingshui','Guochaoxi']

4. The position representation method and interval of the elements in the list

Names[0:-1] Represents the first element from a list names to the last element;

Names[0:-1:2] Represents the first element from the list names to the last element, with a step of 2, each element spaced 1

Names[0:-1:2] Sometimes abbreviated to NAMES[::2] If the step size is 1, then it can be shortened to names[:]

Python Learning (7) about list operations related commands and shallow copy deep copy