List dictionary tuple collection data structure in Python

  • 2020-04-02 14:20:47
  • OfStack

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:


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

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

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

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 = [
        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':'','Tom':''}
    d['Jack']            >>>'
    d['Jim'] = ''    >>>{'Jim': '', 'Jack': '', 'Tom': ''}                del d['Jim']    >>>{'Jack': '', 'Tom': ''}
    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+'' for d2 in list(d.keys())}
            >>>{'Jack': '', 'Tom': ''}

Exercise: loop output key value pairs in the dictionary:
        for name,email in d.items():

Collection of 4.

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


    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.

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