"Python" 10, Python built-in data structure collection

First, the collection

1, the definition of the collection

in [74]: s = {}in [74]: s = {}    #  Empty curly braces are empty dictionaries in [75]: type (s) out[75]: dictin [77]: type (s) out[77]: setin [78]:  help (set) Help on class set in module builtins:class set (object)   |  set ()  -> new empty set object |  set (iterable)  - > new set object |   |  Build an unordered  collection of unique elements. |   |  methods defined  Here:  in [80]: s = set ([1, 2]) in [81]: sout[81]: {1, 2 }in [82]: s = set ("Xxj") in [83]: sout[83]: {' J ',  ' X '}In [84]:  S = {1, 2, 1, 3}IN [85]: SOUT[85]: {1, 2, 3}

collections are unordered, elements cannot be duplicated, elements can be hashed (hash, immutable)

Second, the operation of the collection

1, increase

Z## set.add () In [86]: sout[86]: {1, 2, 3}in [87]: s.add ("a")     #  add a single element in place, the element to be hashed in [88]: sout[88]: {1, 2, 3,  ' a '}in [89]:  s.add (3) in [90]: sout[90]: {1, 2, 3,  ' a '}in [93]: s.add ([1, &NBSP;2])---------------------------------------------------------------------------typeerror                                   Traceback  (most recent  call last) <ipython-input-93-2beaf0c16593> in <module> ()----> 1  S.add ([1, 2]) typeerror: unhashable type:  ' list ' In [94]: help (S.add) In [95]:  s.add ((1, 2)) in [96]: sout[96]: {(1, 2), 1, 2, 3,  ' a '}##  set.update ()   #  adds an iterative object's element In [99]: help (s.update) Help on built-in function update: Update (...)  method of builtins.set instance    update a set with  the union of itself and others.    in [127]: s  = set () In [128]: sout[128]: set () In [129]: type (s) Out[129]: set       in [101]: s.update (------------------------------------------------) -----------------------typeerror                                   Traceback  (most recent call l<ipython-input-101-c184888ad9c5> in  <module> ()----> 1 s.update (typeerror:  ' int '  object is not  iterablein&nbSp [131]: s.update (["a"]) in [132]: sout[132]: {' a '}in [133]: s.update (["A"], [ "B"]) in [134]: sout[134]: {' A ',  ' B '}in [135]: s.update (["A"], ["B"], 1 )-----------------------------------------------------------------------typeerror                               Traceback  (Most recent call last) < Ipython-input-135-fc556b8d9726> in <module> ()----> 1 s.update (["A"], ["B" ], 1) typeerror:  ' int '  object is not iterablein [136]: s.update (["a"],  ["B"],  "XJ") in [137]: sout[137]: {' a ',  ' B ',  ' J ',  ' X '}in [139]:  s.update ([["S",  "B"]])----------------------------------------------------------------------- typeerror                              Traceback  (Most recent call last) < Ipython-input-139-da563f39a191> in <module> ()----> 1 s.update ([["S",  "B"] ]) typeerror: unhashable type:  ' list '

2. By deleting

## set.remove () in [142]: sout[142]: {' a ',  ' B ',  ' J ',  ' X '}In [143]:  s.remove ("a") in [144]: sout[144]: {' B ',  ' J ',  ' X '}in [151]: s.remove (" S ")-----------------------------------------------------------------------keyerror                                Traceback  (Most recent call last) < Ipython-input-151-332efdd48daa> in <module> ()----> 1 s.remove ("s") KeyError:   ' S ' ## set.pop () in [153]: s = {1, 2, 3, 4}in [154]:  S.pop ()     Out[154]: 1In [155]: sOut[155]: {2, 3, 4}In  [156]: s.pop (5)-----------------------------------------------------------------------typeerror                               Traceback  (Most recent call last) < Ipython-input-156-23a1c03efc29> in <module> ()----> 1 s.pop (5) TypeError:  Pop ()  takes no arguments  (1 given) in [157]: s.pop () out[157]: 2in  [158]: s.pop () Out[158]: 3in [159]: s.pop () Out[159]: 4in [160]: s.pop ()----- ------------------------------------------------------------------keyerror                                Traceback  (Most recent call last) < Ipython-input-160-e76f41daca5e> in <module> ()----> 1 s.pop () KeyError:  ' Pop from an empty set ' ## set.discard ()In [165]: help (Set.discard) help on method_descriptor:discard (...)     remove an element from a set if it is a  member.        if the element is not a  member, do nothing.    In [166]: s = {1, 2,  3}in [167]: s.discard (2) In [168]: s.discard (1, 3)------------------------------------ -----------------------------------typeerror                               traceback  (most recent call last) <ipython-input-168-8702b734cbc4> in < Module> ()----> 1 s.discard (1, 3) Typeerror: discard ()  takes exactly  one argument  (2 given) In&nbsP [169]: s.discard (2)    #  element does not exist, will not error in [170]: sout[170]: {1, 3}in  [32]: s.clear () In [33]: sout[33]: set () In [47]: del (s) In [48]:  S-----------------------------------------------------------------------nameerror                               Traceback  (Most recent call last) < Ipython-input-48-f4d5d0c0671b> in <module> ()----> 1 snameerror: name   ' s '  is not defined

Summary:

Remove removes the given element when the element does not exist, throws Keyerror

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

The pop randomly deletes an element and returns it, and the collection is empty to return keyerror,

Clear Empty Collection

3, change

set cannot modify a single element

4. Find

Collections cannot be indexed, collections are not linear, no indexes

Collection does not have a way to access a single element

Collection does not find a method

when doing member operations (in and not), set is much more efficient than List (O (1) and O (n));

O (n) is not necessarily less than O (1) and needs to look at data size

Collection Operations for collections

"Python" 10, Python built-in data structure collection