Road Python module learning --collections

namedtuple generation can use the name to access the content of the element tuple

from collections import namedtuple

namedtuple(

typename: str, field_names: Union[str, Iterable[str]],
               verbose: bool = ..., rename: bool = ...

)

namedtuple (name, attributes)

from collections import namedtuple
Point = namedtuple('point',['x','y','z'])
p = Point(1,2,3)
print(p.x)
print(p.y)
print(p)
# 1
# 2
# point(x=1, y=2, z=3)

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Card = namedtuple('card',['suits','number'])
c1 = Card('红桃',3)
print(c1)
print(c1.number)
print(c1.suits)
# card(suits='红桃', number=3)
#  3
#  红桃

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 deque deque, from the other side can be quickly and additional objects Release

queue

import queue
q = queue.Queue()
q.put(10)
q.put(5)
print(q.qsize())
print(q.get())

from Collections Import the deque 
DQ = the deque ([1,2 ]) 
dq.append ( ' A ' ) # reproducing data from behind 
dq.appendleft ( ' B ' ) # front discharge data 
dq.insert (l, 3 )
 Print ( dq.pop ()) # fetch data from the back 
Print (dq.popleft ()) # front access to data 
# A 
# B

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Counter counter for counting the main

from collections import Counter
c = Counter('sahdqiuopweedwiuyq')
print(c)
Counter({'d': 2, 'q': 2, 'i': 2, 'u': 2, 'w': 2, 'e': 2,
 's': 1, 'a': 1, 'h': 1, 'o': 1, 'p': 1, 'y': 1})

OrderedDict ordered dictionary

When using dict, Key is disordered, when the iterative dict do not determine the order of Key

If you want to keep the order Key, you can use OrderedDict:

from collections import OrderedDict
od = OrderedDict([('a',1),('b',2),('c',3)])
print(od)
print(od['a'])
d = dict([('a',1),('b',2),('c',3)])
print(d)
OrderedDict([('a', 1), ('b', 2), ('c', 3)])
1
{'a': 1, 'b': 2, 'c': 3}

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Dictionary defaultdict with default values

from collections import defaultdict
value = [11,22,33,44,55,66,77,88,99,90]
my_dic = defaultdict(list)
for i in value:
    if i>66:
        my_dic['k1'].append(i)
    else:
        my_dic['k2'].append(i)
print(my_dic)#defaultdict(<class 'list'>, {'k2': [11, 22, )33, 44, 55, 66], 'k1': [77, 88, 99, 90]}

d = defaultdict(lambda :5)
print(d['k'])#5

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