Preface:
Set is divided into two kinds of variable and immutable set, so its add, delete, change and check operation depends on the type of set to decide. Immutable data of course can not be added, deleted or changed, only query, variable collection is slightly less restrictive. In addition to the collection is not required, so there is no way to query directly through the subscripts, while the collection of elements do not have their own key, you can not use the key to query, then how to operate the collection of this data type? The following gives you a list of some of the methods of operation.
1. Collections add new set elements
set1 = {'name', 19, 'python'}
('abc') # Variable sets, direct modification of the original set
print(set1, type(set1))Returns results:
{'python', 'name', 19, 'abc'} <class 'set'>
2. Delete variable set elements
('python') # Delete the specified element, if not, return an error
print(set1)
('name') # Delete the specified element, if not, return to the original collection
print(set1)
() # Randomly remove a variable set element because the set is unordered
print(set1)
() # Empty all elements of the mutable collection
print(set1)
del set1 # Clear the collection
print(set1)Returns results:
{'name', 19, 'abc'}
{19, 'abc'}
{'abc'}
set()
NameError: name 'set1' is not defined
3. Modifying variable collections
Collection elements are immutable types, so they cannot be modified
4. Collection element query method
Collections cannot be queried by means of key-value pairs and are also unordered without subscripts, so they cannot be queried, only traversed.
for i in set1: print(i) # Accessed through iterators its = iter(set1) # Generate an iterator print(next(its)) # Access via next() # or traversing iterators via for in for i in its: print(i) # Immutable and mutable collections are the same traversal operations
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