What is the replication method for python collection set and creating objects
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Set set
Enter:
Bri = set (['brazil',' russia', 'india'])
Print ('india' in bri)
Print ('usa' in bri)
Bric = bri.copy ()
Bric.add ('china')
Print (bric.issuperset (bri))
Bri.remove ('russia')
Print (bri & bric)
# OR bri.intersection (bric)
Output:
True
False
True
{'brazil',' india'}
Explanation:
A collection set is an unordered collection of simple objects. Compared with sequential data structures, collections pay more attention to whether the objects in the collection exist and how many times they occur.
In this example, the set collection is first defined as bri. Exe.
The in statement is then used to determine whether the two objects' india','usa', are in the collection, and the output returns the Bool value TRUE or False depending on whether the object is in the collection.
The collection has the copy () function, which can copy a new collection.
The collection can call .remove () to delete one of the objects.
You can enter the set operation, and in this case, take the intersection set operation.
The output is: {'brazil',' india'}
Create a copy operation for an object
Enter:
#! / usr/bin/python
# Filename: reference.py
Print ('Simple Assignment')
Shoplist = ['apple',' mango', 'carrot',' banana'] mylist = shoplist
# mylist is just another name pointing to the sameobject!
Del shoplist [0]
# I purchased the first item, so I remove it from thelist
Print ('shoplist is', shoplist)
Print ('mylist is', mylist)
# notice that both shoplist and mylist both print the same list without
# the 'apple' confirming that they point to the same object
Print ('Copy by making a full slice')
Mylist = shoplist [:] # make a copy by doing a full slice
Del mylist [0]
# remove first item
Print ('shoplist is', shoplist)
Print ('mylist is', mylist)
# notice that now the two lists are different
Output:
$python reference.py
Simple Assignment
Shoplist is ['mango',' carrot', 'banana']
Mylist is ['mango',' carrot', 'banana']
Copy by making a full slice
Shoplist is ['mango',' carrot', 'banana']
Mylist is ['carrot',' banana']
Explanation:
When you create an object and assign it to a variable, the variable only refers to the object, not the object itself! It can be understood as assigning an address link.
Two sets of examples are given in this example.
First create a list shoplist, and we copy a list mylist. The copy method uses the "=" assignment.
We deleted an element in shoplist and found that the element in mylist had also been deleted.
The second time, we also copied a list mylist. The copy method is assigned using "mylist = shoplist [:]".
We delete an element in shoplist and find that the element in mylist still exists.
In the first, we only copy the address mapping of the object, and the second time, we fully assign the contents of the object.
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