Python built-in data structure 3

Deconstruction

In [8]: LST = [1,2]in [9]: lstout[9]: [1, 2]in [ten]: First,second = LST #解构In [all]: Print (First,second) 1 2

Assign the elements of a linear structure to a variable in the order of elements

The change of deconstruction

in [+]: LST = list (range) in [[]: lstout[22]: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]in []: Head,*mid,tail = lstin []: Hea DOUT[24]: 0In [tailout[25]: 9In []: midout[26]: [1, 2, 3, 4, 5, 6, 7, 8]in []: Head,*_,tail = lstin []: HeadOut []: 0In []: tailout[29]: 9

Python is a convention that uses a single underscore _ to discard the variable

Packaging

in [[]: T = 1,2in [+]: tout[13]: (1, 2) in [+]: type (t) out[14]: Tuplein []: T1 = (+) in [+]: t2 = 1,2in [+]: t1out[ []: (1, 2) in []: t2out[18]: (1, 2)

The package must be ganso.

Collection--No duplicate elements

Definition and initialization

in [+]: s = set () in [+]: sout[32]: Set () in [[]: s = {1,2,3}in]: sout[34]: {1, 2, 3}in [+]: s = Set (range (5)) in [36 ]: sout[36]: {0, 1, 2, 3, 4}

Operation of the collection

Increase

In [PNS]: sout[37]: {0, 1, 2, 3, 4}in [MAX]: S.add (9) #增加单个元素In [[]: sout[39]: {0, 1, 2, 3, 4, 9}in [+]: S.add (9) #增加已经存 In the element, do nothing in [the]: sout[41]: {0, 1, 2, 3, 4, 9}in []: S.update (Range (10,15)) #增加多个元素In []: sout[43]: {0, 1, 2, 3, 4, 9 , 10, 11, 12, 13, 14}

Delete

in [44]: sout[44]: {0, 1, 2, 3, 4,  9, 10, 11, 12, 13, 14}in [45]: s.remove (1) In [46]: sOut[46] : {0, 2, 3, 4, 9, 10, 11, 12, 13, 14}in [47]:  S.pop () out[47]: 0in [48]: sout[48]: {2, 3, 4, 9, 10, 11, 12,  13, 14}in [49]: s.pop () Out[49]: 2in [50]: s.pop () Out[50]: 3In [ 51]: s.pop () Out[51]: 4in [52]: s.pop () Out[52]: 9in [53]: s.pop () Out[53]:  10in [54]: s.pop () Out[54]: 11in [55]: s.discard () In [56]: sOut[56]:  {12, 14} 

• Remove removes the given element, the element does not exist throw Keyerror

• Discard Delete the given element, the element does not exist, nothing is done

• Pop randomly deletes an element and returns the set as empty, throwing keyerror

• Clear Empty Collection

A collection cannot modify a single element, cannot be found by an index, a collection does not have access to a single element, the collection element has no order, and the element must be hashed

Set operation

Intersection, set, difference set, differential set

In [the]: S1 = {1,2,3}in []: s2 = {2,3,4}in []: s1.intersection (S2) out[59]: {2, 3}in []: S1 & s2out[60]: {2, 3}in [A]: in [s1.union]: S2 out[61]: {1, 2, 3, 4}in [+]: S1 | S2OUT[62]: {1, 2, 3, 4}in [+]: in []: s1.difference (S2) out[63]: {1}in [+]: s1-s2out[64]: {1}in [+]: in []: S1.sym Metric_difference (S2) out[65]: {1, 4}in [+]: S1 ^ s2out[66]: {1, 4}

The judgment of the collection

In []: S1 = {1,2,3,4}in []: s2 = {2,3}in []: S2.issubset (S1) out[69]: Truein []: S1.issuperset (S2) out[70]: Truein [ []: in [+]: in []: S1.isdisjoint (S2) # Determine if two sets have intersection, if there is a intersection return False, no intersection returns TRUEOUT[71]: False

Dictionary--is a key-value structure

Definition and initialization

In [the]: D = {}in []: D out[73]: {}in []: D = dict{}in []: D = dict () in []: dout[76]: {}in [all]: D = {' A ': 1, ' B ': 2} In [the]: dout[78]: {' A ': 1, ' B ': 2}in [+]: D = dict ([' A ', 1], (' B ', 2)]) in []: dout[80]: {' A ': 1, ' B ': 2}in [Bayi]: D = Dict.fromkeys (Range (5), ' AB ') in []: dout[82]: {0: ' ab ', 1: ' Ab ', 2: ' AB ', 3: ' AB ', 4: ' AB '}

Add, modify

In [the]: dout[83]: {0: ' ab ', 1: ' Ab ', 2: ' AB ', 3: ' AB ', 4: ' AB '}in [+]: in [+]: d[' a '] = 5In []: dout[85]: {0: ' ab ', 1 : ' AB ', 2: ' AB ', 3: ' AB ', 4: ' Ab ', ' a ': 5}in [[D.update]: (' C ', 6)]) in []: dout[87]: {0: ' ab ', 1: ' Ab ', 2: ' AB  ', 3: ' AB ', 4: ' Ab ', ' a ': 5, ' B ': 5, ' C ': 6}in [in]: D.update ({' d ': 2, ' R ': 6}) in []: dout[89]: {0: ' ab ', 1: ' Ab ', 2: ' AB ', 3: ' AB ', 4: ' Ab ', ' a ': 5, ' d ': 2, ' B ': 5, ' C ': 6, ' R ': 6}

Delete

In [the]: D.pop (0) out[91]: ' AB ' in [the]: dout[92]: {1: ' AB ', 2: ' AB ', 3: ' AB ', 4: ' Ab ', ' a ': 5, ' d ': 2, ' B ': 5, ' C ': 6, ' R ': 6}in []: D.popitem () #随机删除Out [[]: (1, ' AB ')

The traversal of a dictionary

in [100]: dout[100]: {' B ': 5,  ' C ': 6,  ' R ':  6}in [101]: for  x in d:     ...:     print (x)       ...:     bcrin [102]: d.keys () Out[102]: dict_keys ([' B ',  ' C ',  ' R ']) In [103]: d.values () out[103]: dict_values ([5, 6, 6]) In [ 104]: d.items () out[104]: dict_items ([' B ',  5),  (' C ',  6),  (' R ',  6)]) In  [105]: for v in d.values ():     ...:      print (v)      ...:     566In [106]: for  X in d.items ():      ...:     print (x)       ...:      (' B ',  5) (' C ',  6) (' R ',  6) in [107]:  for k,v in d.items ():      ...:     print (k,v)       ...:     b 5c 6r 6

The key of the dictionary cannot be duplicated, it needs to be hashed

This article from "Thick tak" blog, declined reprint!

Python built-in data structure 3