small data pool
Small data pool. Int str is within a certain range, if the two values are the same, in order to save memory, share a memory address.
int: -5 ~ 256
str: 1, if there are non-letter elements, it is not a small data pool.
2, A single letter *int (21) exists in a small data pool.
The rest of the types do not exist.
is
Determine whether the memory addresses of two variables are the same
id
the memory address of the variable
collection set
An element enclosed in {} is a set, and set() represents an empty set. Collections are unordered! ! ! ! ! ! ! ! ! ! !
increase
set1 = {'alex', 'WuSir', 'RiTiAn', 'egon', 'barry'}
set1.add('Taibai' ) # Add in disorder
print (set1)
set1.update('abc' ) # similar to extend iterative addition
set1.update([111, 2222, 333]) print(set1)
delete
#remove remove by element set1.remove('RiTiAn') print(set1) #Randomly delete, there is a return value pop print(set1.pop()) print(set1) #empty clear set1.clear() print(set1) #delete the whole del del set1 print (set1)
check
set1 = {'alex', 'WuSir', 'RiTiAn', 'egon', 'barry'}
for i in set1:
print(i)
intersection & intersection
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
set3 = set1 & set2
print(set3)
print(set1.intersection(set2))
union | union
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
print(set1 | set2)
print(set1.union(set2))
差集 - difference
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
print (set1 - set2) # unique to set1
print (set2.difference(set1)) # unique to set2
Anti-intersection^symmetric_difference
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
print(set1 ^ set2)
print(set1.symmetric_difference(set2))
Subset Superset
set1 = {1, 2, 3}
set2 = {1, 2, 3, 4, 5, 6}
print (set1 < set2) # True set1 is a subset of set2
print (set1.issubset(set2)) # True set1 is a subset of set2
print (set2 > set1) # True set2 is a superset of set1
print (set2.issuperset(set1)) # True set2 is a superset of set1