Summary of common methods for Python collections

Data type: Int/str/bool/list/dict/tuple/float/set (set type natural deduplication)

I. Definition of a collection

s = set () #定义空集合

s = {' A ', ' B ', ' C ', ' d '} #集合不是key-value-shaped, no colon

The set is unordered and cannot be evaluated by subscript.

Second, set assignment value

S.add ()

s = {' A ', ' B ', ' C ', ' d '}
S.add (' Ijk ')  difference between #注意add and update  
# s.update (' FGH ')
Print (s)

Output Result:

{' d ', ' Ijk ', ' C ', ' B ', ' A '}

S.update ()

Output Result:

{' F ', ' B ', ' G ', ' d ', ' a ', ' C ', ' H '}

s = Set ()

s = set (' Cheeseshop ')
Print (s)

Output Result:

{' s ', ' e ', ' P ', ' h ', ' O ', ' C '}

Third, delete the collection element

S.remove ()
s = set (' Cheeseshop ')
S.remove (' er ')  # Delete non-existent will error
S.remove (' e ')
Print (s)

s.pop () #随机删除一个

s.discard (' er ')  #如果删除的元素存在, delete, do not exist do not handle

del s # Delete Collection

Iv. Collection of common operations

S-= set (' Copy ') equivalent to S = S-set (' copy ')

Take intersection

S.intersection (S1) equivalent to S & S1

Fetch and set

S.union (S1) equivalent to S | S1

Take the difference set

S.difference (S1) is   equivalent to  s-s1

Summary of common methods for Python collections