Chapter 1 important data structures in python (I) and python Data Structures

Chapter 1 important data structures in python (I) and python Data Structures

Recently, due to work needs, I used the O & M automation platform of the python development company. So I found this book and started my study on python in conjunction with the official manual.

I. List

[Meaning ]:The list is represented in parentheses and separated by commas (,) (different data types can be used), as stated in the following statement:

1 >>> language = ['Chinese ', 'English', 'Japanese ese '] 2 >>> contries = ['China', 'amercia', 'England ', 'Japan '] 3 4 >>> edward = ['edward gumby', 42] # different data types 5 >>> john = ['John Smith ', 50] 6> database = [edward, john] # The list can be nested.

[Operation]: Access, insert, delete, and calculate the maximum value, minimum value, and length.

1. Access: You can use indexes or shards to traverse the list, and the index can access the value at a certain position. The sharding can flexibly access a certain range of values, as shown below:

1 >>> language = ['China', 'inc ', 'nginx'] 2 # index access 3> language [0] 4 'China' 5 6 # partition access 7 # The first index element is included in the partition, the second index is not included in the Part 8 # You can set the part Step 9> language [:] 10 ['China', 'inc ', 'nginx'] 11 >>> language [0: 3] 12 ['China', 'English ', 'nginx'] 13 >>> language [0: 2] 14 ['China ', 'inc'] 15 >>> language [] 16 ['inc'] 17 # Set the step size to 218 >>>> num = [1, 2, 3, 4, 5, 6, 7, 8, 9] 19 >>> num [0: 9:2] 20 [1, 3, 5, 7, 9]

21 >>> num = [1, 2, 3]
22 >>> max (num)
23 3
24 >>> min (num)
25 1
26 >>> len (num)
27 3

2. You can modify, insert, or delete a list.

1 # modify an element in the list: Index Assignment 2> num = [1, 2, 3] 3> num [0] = 5 # assign a value to an existing location index, otherwise, the error 4 >>> num 5 [5, 2, 3] 6 7 # modify the value of a range in the list: partition assignment 8 >>> num [2:] = [6, 7, 9] # The number of partition assignment elements can be 9> num10 [5, 2, 6, 7, 9] 11 12 # delete an element 13> del num [4] 14> num15 [5, 2, 6, 7]

[Method]For the list, python has many built-in methods for operation. The following are commonly used:

1 # append method: Used to add elements at the end of the list. This method directly modifies the original list and returns the new list after modification. 2 >>> str = ['A ', 'B', 'C', 'D'] 3 >>> str. append ('E') 4 >>> str 5 ['A', 'B', 'C', 'D', 'E'] 6 7 # count method: count the number of times an element appears in the list. 8 >>> str = ['A', 'B', 'C', 'D'] 9 >>> str. count ('A') 10 111 12 # extend method: list. extend (L), L refers to the list object 13 # using another list to expand a list is equivalent to two list connections, 14 # but different from the connection operation, because the extend method directly modifies the original list and returns the result, 15 # The Connection operation does not affect the original list value 16 >>> str1 = ['hello, '] 17 >>> str2 = ['World'] 18 >>> str1.extend (str2) 19 >>> str120 ['hello ,', 'World'] 21 22 >>> str3 = ['a'] 23 >>>> str4 = ['5'] 24 >>>> str3 = str3 + str4 # efficiency without extend high 25 >>> str326 ['A ', '5'] 27 28 # index method: returns the first index location of a match. 29 >>> knight = ['we', 'you', 'we ', 'Me', 'hes'] 30 >>> knight. index ('we') 31 032 33 # insert method: list. insert (I, x) insert x to the position 34> knight. insert (1, 'she') 35 >>> knight36 ['we', 'she', 'you', 'we', 'me ', 'hes'] 37 38 # remove Method: list. remove (x) 39 # Delete the first occurrence element of X in the list. 40 >>> knight = ['we', 'she', 'you', 'we ', 'Me', 'hes'] 41 >>> knight. remove ('we') 42 >>> knight43 ['she', 'you', 'we', 'me', 'hes'] 44 45 # reverse method: store elements in Reverse Order 46 >>> str = ['A', 'B'] 47 >>> str. reverse () 48 >>> str49 ['B', 'a'] 50 51 # sort method: list. sort (key = None, reverse = False) 52 # directly change the order of the original list, instead of changing the copy. For this requirement, such as 53 # Simply sort the copy, you cannot directly use sort54> num = [1, 3, 2, 4] 55> num without changing the original list. sort () 56 >>> num57 [1, 2, 3, 4] 58 59 # pop method: list. pop ([I]) 60 # Delete the element value at the specified index location and return the value 61 >>> num = [1, 2, 3, 4] 62 >>> num. pop (3) 63 4

[Examples ]:Simulate stack operations and queue operations

STACK: Back-to-first-out

 1 >>> stack = [3, 4, 5] 2 >>> stack.append(6) 3 >>> stack.append(7) 4 >>> stack 5 [3, 4, 5, 6, 7] 6 >>> stack.pop() 7 7 8 >>> stack 9 [3, 4, 5, 6]10 >>> stack.pop()11 612 >>> stack.pop()13 514 >>> stack15 [3, 4]

Queue: FIFO

 1 >>> from collections import deque 2 >>> queue = deque(["Eric", "John", "Michael"]) 3 >>> queue.append("Terry")           # Terry arrives 4 >>> queue.append("Graham")          # Graham arrives 5 >>> queue.popleft()                 # The first to arrive now leaves 6 'Eric' 7 >>> queue.popleft()                 # The second to arrive now leaves 8 'John' 9 >>> queue                           # Remaining queue in order of arrival10 deque(['Michael', 'Terry', 'Graham'])