day09-- basic data types and a set of built-in functions

First, the definition set

1.1 Definitions: {} in the plurality of elements separated by commas, immutable data element type, and arrangement of the elements are unordered.

List_1 = >>> [ ' Egon ' , ' MALE ' , 18 is , [ ' Play ' , ' Read ' ]]
 >>> S = SET (list_1) 
Traceback (MOST Recent Last Call): 
  File " <pyshell. 1 #> " , Line . 1 , in <Module1> 
    S = sET (list_1) 
TypeError: unhashable type: ' List ' 
>>>  

element must be prompted to set a hash, i.e., immutable type

1.2 are unordered collection of elements, and is not repeated

>>> list1 = [1,1,2,2,3,3]
>>> s = set(list1)
>>> print(s)
{1, 2, 3}
>>>

Note: s = {} default dictionary is empty

1.3 Type Conversion

Collection can be converted into iterables binding, but if the object is a container type may iteration, then the child element iterables must be immutable data type

1.4 built-in method

(1) on the intersection s1 & s2

friends1 = { " ZERO " , " Kevin " , " Jason " , " Egon " } # friends are user 1 
friends2 = { " of Jy " , " Ricky " , " Jason " , " Egon " }    # user 2 friends are 
= & friends1 RES friends2 
RES = friends1.intersection (friends2)
 Print (RES) 

{ ' Egon ', 'jason'}

(2) taken and set s1 | s2

friends1 = { " ZERO " , " Kevin " , " Jason " , " Egon " } # friends are user 1 
friends2 = { " of Jy " , " Ricky " , " Jason " , " Egon " }    # user 2 friends are 
= friends1 RES | friends2 
RES = friends1.union (friends2)
 Print (RES) 

{ ' Egon ' ,'kevin', 'ricky', 'Jy', 'zero', 'jason'}

(3) taking the difference set s1 - s2 or s1.difference (s2)

Take f1 unique friend

friends1 = { " ZERO " , " Kevin " , " Jason " , " Egon " } # friends are user 1 
friends2 = { " of Jy " , " Ricky " , " Jason " , " Egon " }    # user 2 friends are 
= friends1 RES - friends2 
RES = friends1.difference (friends2)
 Print (RES) 

{ ' Kevin ', 'zero'}

Take f2 unique friend

friends1 = { " ZERO " , " Kevin " , " Jason " , " Egon " } # friends are user 1 
friends2 = { " of Jy " , " Ricky " , " Jason " , " Egon " }    # user 2 friends are 
= friends2 RES - friends1 
RES = friends1.symmetric_difference (friends2)
 Print (RES) 

{ ' Ricky ', ' You ' }

(4) symmetric difference f1 ^ f2

friends1 = { " ZERO " , " Kevin " , " Jason " , " Egon " } # friends are user 1 
friends2 = { " of Jy " , " Ricky " , " Jason " , " Egon " }    # user 2 friends are 
^ = friends2 RES friends1
 Print (RES) 

{ ' Kevin ' , ' of Jy ' ,'ricky', 'zero'}

(5) a parent subset (comprising Relations)

l, 2,3 = {S1 } 
S2 = {1, 2,4 }
                 # no inclusion relationship, the following are comparative False 
Print (s1.issuperset (S2))
 Print (S1> S2)
 Print (S1 <S2)

l, 2,3 = {s1 } 
s2 = {1,2 }
 Print (s1.issubset (s2))
 Print (s1> s2)       # When s1 is greater than or equal to s2, s1 is to say the father s2

l, 2,3 = {S1 } 
s2 = {l, 2,3 }
 Print (S1 == s2) # S1 and s2 each other Sons

1.4 deduplication

Note: 1, only for immutable types deduplication

2, can not guarantee that the original order

l = [1,'a','b',1,1,2,3]
l = list(set(l))
print(l)

[1, 2, 3, 'a', 'b']

1.5 Other built-in method

（1） discard

l, 2,3 = {S } 
s.discard ( . 4)     # delete the element does not exist, do Nothing 
Print (S)

remove

l, 2,3 = {S } 
s.remove ( . 4)      # remove elements does not exist, an error 
Print (S)

pop

>>> s = {1,2,3}
>>> res=s.pop()
>>> print(res)
1
>>>

（2）update

S = {l, 2,3 >>> }
 >>> s.update ([4,5,6 ])
 >>> Print (S) 
{ . 1, 2,. 3,. 4,. 5,. 6 }
 >>> s.update ([. 7, [8, 9 are ]]) 
Traceback (MOST Recent Last Call): 
  File " <pyshell # 16> " , Line. 1, in <Module1> 
    s.update ([ . 7, [8, 9 are ] ]) 
TypeError: unhashable type: ' List ' 
>>>  

child element of the target object must be a hash of data types (i.e., immutable data type)

（3）add

s = {1,2,3}
s.add(4)
print(res)

Other methods to understand

day09-- basic data types and a set of built-in functions

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