Python Dictionary Exercise and Solutions

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Programs

Question 1 : Write a Program to rename a key from the dictionary.

Given Dictionary: 

employee_detail = {
    "name" : "Tim",
    "age" : 25,
    "gender" : "Male"
}

Expected Output: 

{'age': 25, 'gender': 'Male', 'first_name': 'Tim'}

Solution:

employee_detail = {
    "name" : "Tim",
    "age" : 25,
    "gender" : "Male"
}

employee_detail["first_name"]  = employee_detail.pop("name")

print(employee_detail)

Output:

{'age': 25, 'gender': 'Male', 'first_name': 'Tim'}

Question 2 : Write a Program to remove a list of keys from the dictionary.

Given Dictionary: 

marks = {
    "Bill" : 78,
    "Tim" : 75,
    "Steve" : 80
}

to_remove = ["Tim", "Jeff"]

Expected Output: 

{'Bill': 78, 'Steve': 80}

Solution:

We can achieve this task using the two approaches:

Approach 1: Using the for loop

marks = {
    "Bill" : 78,
    "Tim" : 75,
    "Steve" : 80,
    "Jeff" : 79
}

to_remove = ["Tim", "Jeff"]

for name in to_remove:
    if name in marks:
        marks.pop(name)
        
print(marks)

Approach 2: Using comprehension

marks = {
    "Bill" : 78,
    "Tim" : 75,
    "Steve" : 80,
    "Jeff" : 79
}

to_remove = ["Tim", "Jeff"]

new_marks = {name:marks[name] for name in marks.keys() - to_remove}# in to_remove:
    
        
print(new_marks)

Output:

{'Bill': 78, 'Steve': 80}

Question 3 : How can we find maximum value from the dictionary?

Given Dictionary: 

marks = {
    "Bill" : 78,
    "Tim" : 75,
    "Steve" : 80
}

Expected Output: 

Steve

Solution:

Using the max() function.

marks = {
    "Bill" : 78,
    "Tim" : 75,
    "Steve" : 80
}

print(max(marks, key = marks.get))

Output:

Steve

Question 4 : Create a new dictionary with specific keys from the old one

Given Dictionary: 

marks = {
    "Bill" : 78,
    "Tim" : 75,
    "Steve" : 80,
    "Jeff" : 79
}

Expected Output: 

{'Tim': 75, 'Jeff': 79}

Solution:

Approach 1: Using a for loop and a temporary variable.

marks = {
    "Bill" : 78,
    "Tim" : 75,
    "Steve" : 80,
    "Jeff" : 79
}

new_keys = ["Tim", "Jeff"]
new_dict = {}
for name in new_keys:
    new_dict[name] = marks[name]
    
print(new_dict)

Approach 2: Using dictionary comprehension.

marks = {
    "Bill" : 78,
    "Tim" : 75,
    "Steve" : 80,
    "Jeff" : 79
}

new_keys = ["Tim", "Jeff"]

new_dict = {name: marks[name] for name in new_keys}
    
print(new_dict)

Approach 3: Using the update method.

marks = {
    "Bill" : 78,
    "Tim" : 75,
    "Steve" : 80,
    "Jeff" : 79
}

new_keys = ["Tim", "Jeff"]
new_dict = {}
for name in new_keys:
    new_dict.update({name: marks[name]})
    
print(new_dict)

Output:

Steve

Question 5 : Check if the value is present in the dictionary.

Given Dictionary: 

marks = {"Bill" : 87, "Steve" : 85, "Jeff" : 81}

Value to check: 

81

Solution:

Approach 1: Using values() method.

marks = {"Bill" : 87, "Steve" : 85, "Jeff" : 81}
value = 81

if value in marks.values():
    print("Value is Present")
else:
    print("Value is not Present")

Approach 2: Using for loop.

marks = {"Bill" : 87, "Steve" : 85, "Jeff" : 81}
value = 81

for i in marks:
    if value == marks[i]:
        print("Value is Present")
        break;
else:
    print("Value is not presnt")

Output:

Value is Present

Question 6 : We have 3 dictionaries of marks of marks. How can we create a single dictionary by nesting three dictionaries in the one dictionary.

Given Dictionaries: 

bill = {1 : 82, 2 : 84, 3 : 86}
steve = {1 : 81, 2 : 82, 3 : 89}
jeff = {1 : 84, 2 : 85, 3 : 88}

Expected Output:

{'bill': {1: 82, 2: 84, 3: 86}, 'steve': {1: 81, 2: 82, 3: 89}, 'jeff': {1: 84, 2: 85, 3: 88}}

Solution:

bill = {1 : 82, 2 : 84, 3 : 86}
steve = {1 : 81, 2 : 82, 3 : 89}
jeff = {1 : 84, 2 : 85, 3 : 88}

marks = {"bill" : bill, "steve" : steve, "jeff" : jeff}

print(marks)

Output:

{'bill': {1: 82, 2: 84, 3: 86}, 'steve': {1: 81, 2: 82, 3: 89}, 'jeff': {1: 84, 2: 85, 3: 88}}

Question 7 : We have 3 dictionaries of marks. How can we create a single dictionary by nesting three dictionaries in the one dictionary?

Given Dictionaries: 

bill = {1 : 82, 2 : 84, 3 : 86}
steve = {1 : 81, 2 : 82, 3 : 89}
jeff = {1 : 84, 2 : 85, 3 : 88}

Expected Output:

{'bill': {1: 82, 2: 84, 3: 86}, 'steve': {1: 81, 2: 82, 3: 89}, 'jeff': {1: 84, 2: 85, 3: 88}}

Solution:

bill = {1 : 82, 2 : 84, 3 : 86}
steve = {1 : 81, 2 : 82, 3 : 89}
jeff = {1 : 84, 2 : 85, 3 : 88}

marks = {"bill" : bill, "steve" : steve, "jeff" : jeff}

print(marks)

Output:

{'bill': {1: 82, 2: 84, 3: 86}, 'steve': {1: 81, 2: 82, 3: 89}, 'jeff': {1: 84, 2: 85, 3: 88}}

Question 9 : How can we check if the dictionary is empty?

Solution:

dict1 = {}
dict2 = {1:"one", 2:"two"}

if dict1 == dict():
    print("Dictionary dict1 is empty.")

if dict2 == dict():
    print("Dictionary dict2 is empty.")

Output:

Dictionary dict1 is empty.

Question 9 : We have a dictionary with 9 votes for two candidates, ‘a’ and ‘b’. How can we count the number of votes each candidate has got and the winner?

Given Dictionary:

v = {1:'a', 2:'b', 3:'a', 4:'a', 5:'b', 6:'a', 7:'a', 8:'b', 9:'a'}

Solution:

v = {1:'a', 2:'b', 3:'a', 4:'a', 5:'b', 6:'a', 7:'a', 8:'b', 9:'a'}
count = {}

for i in v:
    if v[i] in count:
        count[v[i]] += 1
    else:
        count[v[i]] = 1

print("Final result =",count)

print("Winner =", max(count, key = count.get))

Output:

Final result = {'a': 6, 'b': 3}
Winner = a
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