Python del keyword

The del keyword in Python is used to delete objects like variables, lists, dictionary entries, or slices of a list. Since everything in Python is an object, del helps remove references to these objects and can free up memory

del Keyword removes the reference to an object. If that object has no other references, it gets cleared from memory. Trying to access a deleted variable or object will raise a NameError.

Syntax

del object_name

object_name: name of the object to delete (list, set dictionary, etc).

Del Keyword for Deleting Objects

In the example below, we will delete Gfg_class using del statement.

class Gfg_class:
    a = 20

# creating instance of class
obj = Gfg_class()
          
# delete object
del obj

# we can also delete class
del Gfg_class
  

Deleting Variables

del keyword can be used to delete variables too.

a = 20
b = "GeeksForGeeks"

# delete both the variables
del a, b

# check if a and b exists after deleting
print(a)
print(b)

Output:

NameError: name 'a' is not defined

Explanation: del a, b removes the existence of a and b therefore print() funciton is not able to find them.

List Slicing Using del Keyword

In the program below we will delete some parts of a list (basically slice the list) using del keyword.

a = [1, 2, 3, 4, 5, 6, 7, 8, 9]

# delete second element of 'a'
del a[1]
  
# check if the second element in 'a' is deleted
print(a)
  
# slice 'a' from index 3 to 5
del a[3:5]
  
# check if the elements from index 3 to 5 in 'a' is deleted
print(a)

[1, 3, 4, 5, 6, 7, 8, 9]
[1, 3, 4, 7, 8, 9]

Deleting Dictionary and Removing key-value Pairs

In the program below we will remove few key-value pairs from a dictionary using del keyword.

d = {"small": "big", "black": "white", "up": "down"}
  
# delete key-value pair with key "black" from my_dict1
del d["black"]
  
# check if the  key-value pair with key "black" from d1 is deleted
print(d)

{'small': 'big', 'up': 'down'}

Please refer delattr() and del() for more details.