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1) what is the output of following code?
lst=["1","2","3"]
del lst[10:100]
print(lst)
a) ['1','2','3']
b) Gives Error
c) 123
d) "1" "2" "3" "4"
Ans) a is correct answer, because lst[10:100] is not found to delete an element
2) What is the output of the following code?
lst =[1,2,3,4,5]
print(lst[25])
a)[]
b)12345
c)Give an Error
d)No output produced.
Ans) c
3) What is the output of the following:
numbers = [5, 6, 7, 8, 9]
for i in range(len(numbers) - 1, -1, -1):
print(numbers[i], end=' ')
a) 98765
b) 56789
c) 12345
d) Gives Error
Ans)a
4)What is the output of the following?
lst=[1,2,3,4,5,6,7,8]
lst1=lst[2:9]
print(lst1)
a) It gives Error
b) [1,2,3,4,5,6,7,8]
c) [3,4,5,6,7,8]
d) []
Ans) c
5)Which symbol is used in python to add comments?
a)$
b)//
c)/*.... */
d)#
Ans) d
6) What is the output of the following code?
def funct(message, n):
while(n > 0):
print(message)
n-=1
funct('A', 5)
a)AAAA
b)AAAAA
c)Syntax Error
d)Infinite Loop
Ans) d - Infinite Loop
7) Find the output of the following program:
myList = ['1', '2', '3', '4', '5']
print(myList[10:])
a)[]
b)[1,2,3]
c)It gives Error.
d)1,2,3,4,5
Ans) a
8) What is the output of the following?
lst=[1,2,3,4,5]
lst.remove(11)
print(lst)
a)[1,2,3,4,5]
b)1,2,3,4,5
c)[]
d)ValueError:
Ans) d
9) What is the output of the following?
lst=[1,2,3,4,5]
del lst[9:10]
print(lst)
a)[1, 2, 3, 4, 5]
b)Gives Error
c)1,2,3,4,5
d)[]
Ans) a
10)What is the output of the following?
A=[1,2,3,4,5]
B=A[:]
print(B)
a)1,2,3,4,5
b)[1,2,3,4,5]
c)Gives Error
d)[5,4,3,2,1]
Ans)b
11. Describe Python Dictionary
A Python dictionary is an unordered, mutable collection consisting key-value pairs where each key must be unique and it has a specific value.
Example:
dict = {'name': 'Mike', 'age': 15}
12. Show how to access a value from a dictionary?
A value in a Python dictionary can be accessed by using the key inside square brackets[].
Example:
dict = {'name' : 'John' , 'age' : '18'}
print(dict['name'])
13. Can you access a non-existent key in Python Dictionary?
Python raises a KeyError if you access a non-existent key, because the key does not exist in the dictionary.
Example:
dict = {'name': 'Amy'}
print(dict['age']) # Raises KeyError: 'age'
14. Show how to avoid a KeyError while accessing a dictionary?
Ans) There are 2 ways to avoid the KetError while accessing a dictionary
a)Use the get() method. It returns None if the key is not found and does not raise an error.
b) use if condition for the key
Example:
dict = {'name': 'Alice'}
if('age' in dict):
print(dict['age'])
else:
print('Key not found')
15. Show how to add or update a key-value pair in a dictionary?
Ans) We can assign a value to key. Its value is updated if the key exists and if it does not exist, a new key-value pair is added to the dictionary.
Example:
dict = {'name': 'Bruce'}
# This adds new key-value pair
dict['age'] = 21
# This updates the value of age
dict['age'] = 25
16.How do you remove a key-value pair from a dictionary?
We can use del or the pop() method to remove a key-value pair from Python Dictionary. pop() method returns the value associated with the key.
Example:
dict= {'name': 'Joseph', 'age': 40}
# Removes 'age' key
del dict['age']
# Removes key 'name' and returns its value
dict.pop('name')
17. How to get all the keys, values, or items in a dictionary?
Use the method keys() to get all keys.
Use the method values() to get all values.
Use the method items() to key-value pairs.
Example:
dict = {'name': 'Vincent', 'age': 25}
#get all keys()
my_dict.keys()
#get all values of keys
dict.values()
#get key-value pairs
dict.items()
18. In Python dictionary, can you check if a key exists?
Ans) Yes, we can check using if statement
dict = {'name': 'Mary', 'age': 19}
if ('name' indict):
print("Key exists!")
19. What nested dictionary in Python?
A dictionary which has atleast a key whose value is another dictionary.
Example:
dict = {'person': {'name': 'Jack', 'age': 21}, 'address': {'1154 Park Lane, Newark, CA, 94560'}}
20. Give a difference between a Python dictionary and a list.
A Python dictionary is an unordered collection of key-value pairs. Python list is an ordered collection of elements.
Dictionaries are very efficient for fast key lookups.
21. What method is used to clear all elements from a dictionary?
clear() method to remove all key-value pairs.
Example:
dict = {'name': 'Randy', 'age': 33}
#clears all items
dict.clear()
22. How do you copy a dictionary?
The copy() method creates a shallow copy of the dictionary, which means it copies the dictionary structure itself but does not copy any nested
objects.
Example:
dict = {'name': 'Jack', 'age': 30}
#Using copy()
dict_copy = dict.copy()
23.Show how to iterate over a dictionary?
We can iterate over a dictionary using a for loop using items() to iterate over both keys and values.
Example:
dict = {'name': 'Jack', 'age': 21}
for key, value in dict.items():
print(f"{key}: {value}")
24. What is the difference between pop() and popitem() in Python dictionary?
Use pop() to remove a key-value pair by the key and returns its value.
Use popitem() to remove and return a random key-value pair
25. How to merge two dictionaries?
Use update()
Example:
dictionary1 = {'name': 'Alice'}
dictionary2 = {'age': 25}
dictionary1.update(dictionary2) # Merges dictionary2 into dictionary1
26. What is the purpose of the fromkeys() method?
The fromkeys() method creates a new dictionary from a sequence of keys,and assign None values to them
Example:
my_keys = ['A', 'B', 'C']
#Using fromkeys
my_dict = dict.fromkeys(my_keys)
27. What is enumerate function inside a dictionary?
Enumerate function is used to get position index and corresponding index at the same time.
Example:
dict = {'name' : 'Martin', 'age' : 28}
for i ,x in enumerate(dict):
print(f"{i} - {x})
output:
--------
0 - name
1 - age
28. What is a defaultdict?
A defaultdict is a subclass of dict that provides a default value if a key is not found. We can initialize with a factory function.
Example:
from collections import defaultdict
my_dict = defaultdict(int) # Default value is 0 for missing keys
my_dict['a'] += 1
29. Can dictionary keys be numbers
Yes, dictionary keys can be numbers
Example:
dict={1:12,2:14}
print(dict)
output:
------
{1: 12, 2: 14}
30. How do you check the size of a dictionary?
Use the len() function to get the number of key-value pairs in a dictionary.
Example
dict = {'name': 'Amber', 'age': 32}
print(len(my_dict))
output:
2
31. Show how to access values in a nested dictionary?
nested_dict = {'person': {'name': 'Ronny', 'age': 30}, 'address': {'111 Park street, Newark, CA'}}
print(nested_dict['person']['name'])
32. What is the difference between shallow copy and deep copy of a dictionary?
There is a basic difference between a Shallow and a deep copy is - A shallow copy copies the dictionary structure but not the nested objects
33. How do you efficiently update a dictionary using another dictionary?
The update() method updates the dictionary with the keys and values from another dictionary
Example:
dict1 = {'name': 'Alice'}
dict2 = {'age': 25}
dict1.update(dict2)
print(dict1)
34)
What is the difference between a mutable data type and an immutable data type?
Mutable data types:
Definition: Mutable data types are those that can be modified after their creation.
Examples: List, Dictionary, Set.
Immutable data types are those that cannot be modified after their creation.
Examples: Numeric (int, float), String, Tuple.