Python Collections Class

Import Collections
c = Collections. Counter (' Abcdeabcdabcaba ')
Print (c)

Results: Counter ({' A ': 5, ' B ': 4, ' C ': 3, ' d ': 2, ' E ': 1})
Conclusion: The number of occurrences of a statistical string

Import Collections
c = Collections. Counter (' Abcdeabcdabcaba ')
Print (c)

ret = C.most_common (2)
Print (ret)

Results: [(' A ', 5), (' B ', 4)]
Conclusion: The two most frequently occurring strings are counted

Import Collections
c = Collections. Counter (' Abcdeabcdabcaba ')
Print (c)
Print (sorted (c))
Results: [' A ', ' B ', ' C ', ' d ', ' e ']
Conclusion: List all the unique elements

Import Collections
c = Collections. Counter (' Abcdeabcdabcaba ')
Print (c)
For k,v in C.items ():
    Print (K,V)
Results:

　Counter ({' A ': 5, ' B ': 4, ' C ': 3, ' d ': 2, ' E ': 1})
A 5
C 3
E 1
D 2
B 4

Conclusion: Count the occurrences of each string

Ordereddict

Import Collections
DIC = collections. Ordereddict ()
dic[' K3 '] = ' v3 '
dic[' k1 '] = ' v1 '
dic[' k2 '] = ' v2 '
Print (DIC)
Results: ordereddict ([' K3 ', ' V3 '), (' K1 ', ' v1 '), (' K2 ', ' V2 ')])
Conclusion: Using lists to maintain an ordered dictionary

Defaultdict

Import Collections
values = [11,22,33,44,55,66,77,88,99]
DIC = collections.defaultdict (list)   #设置缺省为list类型
For value in values:
    If value <66:
        dic[' K1 '].append (value)
    Else
        dic[' K2 '].append (value)
Print (dic[' K1 ')
Print (dic[' K2 ')

Do not use the default dictionary

values = [11,22,33,44,55,66,77,88,99]
Dic1 = {' K1 ': []}
Dic2 = {' K2 ': []}

For value in values:
    If value < 66:
            dic1[' K1 '].append (value)
    Else
            dic2[' K2 '].append (value)
Print (DIC1)
Print (DIC2)
Results:

　　{' K1 ': [11, 22, 33, 44, 55]}
{' K2 ': [66, 77, 88, 99]}

Conclusion: The value of DIC1,DIC2 must be established as a list empty table

Namedtuple (named Ganso)

Import Collections

Test = collections.namedtuple (' Test ', (' x ', ' y ', ' z '))

obj = Test (11,22,33)
Print (obj.x)

Results: 11
Conclusion: For the meta-ancestor, access to the data can only be accessed by subscript, but for a named Ganso, you can construct a new class (such as test) and then invoke the method to implement

Bidirectional queue

Import Collections

dq = collections.deque ()

One-way queues

Import queue
Q = queue. Queue ()
Q.put ("123")
R = Q.get ()
Print (R)

Python Collections Class