Data type classification
Variable immutable:
1. Variable: List, Dictionary
2. immutable: string, number, tuple
access order:
1. Direct Access: Digital
2. sequential access: strings, lists, tuples
3. Mapping: dictionary
storage number of elements:
1. type containers: lists, tuples, dictionaries
2 atomic types: numeric, string
set
By different sets of elements, the set is a set of hash values disordered array can be used as a dictionary Key
1. different elements
2. unordered
3. The elements in the set must be immutable type, such as: string digital tuple
set of definitions:
s={1,2,5,6,7,3,5}
for i in s:
print(i)
>>>
1
2
3
5
6
7
set definitions:
s=set('hello') print(s) # >>>{'o', 'l', 'e', 'h'} s=set(['raito','raito','nb']) print(s) # >>># {'nb', 'raito'}
method:
1,2,3,4,5,6 = {S }
# Add
s.add ( ' S ' )
s.add ( ' . 3 ' )
s.add ( . 3 )
Print (S) # { '. 3',. 1 , 2,. 3,. 4,. 5,. 6, 'S'}
# empty
# s.clear ()
# Print (S) #set ()
# copies
S1 = s.copy ()
Print (S1) # {. 1, 2 ,. 3,. 4,. 5,. 6, '. 3', 'S'}
S = { ' A ' , ' B ' , 1,2,3,4,5,6 }
# random puncturing
# s.pop ()
# Print (S)
# Specifies to delete
# s.remove ( 'b')
# s.remove ( 'hellol') # remove an element does not exist will get an error
# s.discard ( 'ASAS') # remove an element does not exist without error
# Print (S)
Set operations (common operation):
python_l = [ ' LCG ' , ' SZW ' , ' ZJW ' , ' LCG ' ] linux_l = [ ' LCG ' , ' SZW ' , ' SB ' ] P_s = SET (python_l) L S = SET (linux_l) # intersection Print ( P_s, L S) Print (p_s.intersection (L S)) Print (& P_s L S) # and set Print (p_s.union (L S)) Print(P_s | L S) # set difference: I have you do not have a Print ( ' set difference ' , p_s- L S) Print (p_s.difference (L S)) Print ( ' set difference ' , l_s- P_s) Print (l_s.difference (P_s)) # deduplication portion of the rear set of requirements and set: cross complement Print ( ' cross complement ' , p_s.symmetric_difference (L S)) Print ( ' cross complement ' , P_s ^ L S)