List dictionary tuple collection data structure in Python

This article summarizes the list, dictionary, tuple and collection data structure in Python in detail. Share with you for your reference. Specific analysis is as follows:

List:

shoplist = ['apple', 'mango', 'carrot', 'banana']

Dictionary:

di = {'a':123,'b':'something'}

Collection:

jihe = {'apple','pear','apple'}

Tuples:

t = 123,456,'hello'

List 1.

Empty list: a=[]

Function method:

          a.append(3)     　　>>>[3]    

          a.extend([3,4,5])     　　>>>[3,3,4,5]    # Add a list sequence 

          a.insert(1,'hello')    　　  >>>[3,'hello',3,4,5]

          a.remove(3)        　　　  >>>['hello',3,4,5] # Delete the first one that appears 3 , there is no 3 Is an error 

          a.pop()        　　　　　　>>>['hello',3,4]

          a.pop(0)        　　　　　　>>>[3,4]

          a.index(4)       　　 >>>1    # Returns the first one that appears 4 The subscript 

          a.count(3)        　　>>>1    # List element 3 The number of 

          a.sort        >>>[3,4]    # The sorting 

          a.reverse()        >>>[4,3]    # trans 

Delete element method:

        a.remove(3)    # Deletes an element by value, removing the first element as an argument 

        a.pop()       # The element is deleted by subscript, the last value of the list is deleted by default, and the element with parameter is deleted by subscript 

        del a[0]       # Delete an element by subscript, 

            del a[2:4] # delete a Table subscript for 2,3 The elements of the 

        del a[:]   # delete a List all elements 

        del a       # Delete the list 

List derivation:

        vec = [2,4,6]    

         [3*x for x in vec if x<6]    >>>[6,12]    3*2,3*4

        vec2 = [1,2,3]

        [x*y for x in vec for y in vec2]    >>>[2,4,6,4,8,12,6,12,18]

Nested list derivation:

        mat = [

        [1,2,3],

        [4,5,6],

        [7,8,9]

        ]

        print ([[row[i] for row in mat] for i in [0,1,2]])    

        >>>[[1, 4, 7], [2, 5, 8], [3, 6, 9]]

Thinking: what's the difference between the results of list (zip(mat)) and list (zip(*mat)

2. A tuple

      Null tuple: t = ()
      Tuple assignment: t = (123,345)
                    T [0]                 > > > 123
3. The dictionary      

    d = {'Jack':'jack@mail.com','Tom':'Tom@main.com'}

    d['Jack']    　　　　　　　　>>>'jack@mail.com

    d['Jim'] = 'Jim@sin.com'    >>>{'Jim': 'Jim@sin.com', 'Jack': 'jack@mail.com', 'Tom': 'Tom@main.com'}            
　  del d['Jim']    >>>{'Jack': 'jack@mail.com', 'Tom': 'Tom@main.com'}

    list(d.keys())    # Returns an unordered list of all the keywords in the dictionary 

    sorted(d.keys()) # A sorted list of all the keywords in a dictionary is returned 

    dict()    # The constructor can be written directly from key-value Create a dictionary in pairs 

    dict([('Tim',123),('Tiny',234)])    >>>{'Tiny': 234, 'Tim': 123}

     

Derivation to create a dictionary:

        {d2:d2+'@main.com' for d2 in list(d.keys())}

            >>>{'Jack': 'Jack@main.com', 'Tom': 'Tom@main.com'}

Exercise: loop output key value pairs in the dictionary:

        for name,email in d.items():

            print(name,email)

Collection of 4.

Empty set: A = set() does to create an empty set, you must use set()

Presentation:

    basket = {'apple','orange','apple'}    >>>{'orange', 'apple'}    # Note that duplicate elements show only one 

    'apple' in basket              >>>True

    'pear' in basket            >>>False

Mathematical operation of set:      

        a = set('ababcdabca')        >>>{'c', 'b', 'a', 'd'}

        b = {'a','b','m'}            >>>{'b', 'a', 'm'}

        a - b        >>>{'c', 'd'}

        b - a        >>>{'m'}

        a | b        >>>{'c', 'd', 'b', 'a', 'm'}

        a & b        >>>{'a','b'}

        a ^ b        >>>{'c','d','m'}

Set derivation formula:

       {x for x in a if x not in 'ab'}    >>>{'c','d'}

I hope this article has helped you with your python programming.