Python Exercise3

1. Create an empty dictionary, add four keys and values to the dictionary. Print the keys from the dictionary.

dic={}

dic[‘O’]=”Oxyzen”

dic[‘Ca’]=”Calcium”

dic[‘Na’]=”Sodium”

dic[‘H’]=”Hydrogen”

print(dic)

print(dic.keys())

 

2. Create a dictionary, dic={‘O’:’Oxyzen’,’Ca’:’Calcium’,’Na’:’Sodium’,’H’:’Hydrogen’}. Print the values from the dictionary.

dic={‘O’:’Oxyzen’,’Ca’:’Calcium’,’Na’:’Sodium’,’H’:’Hydrogen’}

print(dic)

print(dic.values())

 

3. Create a dictionary, dic={‘O’:’Oxyzen’,’Ca’:’Calcium’,’Na’:’Sodium’,’H’:’Hydrogen’}. Print the items from the dictionary.

dic={‘O’:’Oxyzen’,’Ca’:’Calcium’,’Na’:’Sodium’,’H’:’Hydrogen’}

print(dic)

print(dic.items())

 

4.Create a dictionary marks={‘maths’:97,’science’:98,’history’:78}. Remove the key science from the dictionary.

marks={‘maths’:97,’science’:98,’history’:78}

del marks[‘science’]

print(marks)

 

5. Create a dictionary marks and clear all the items from the dictionary.

marks={‘maths’:97,’science’:98,’history’:78}

marks.clear()

print(marks)

 

6. Create a dictionary, delete the dictionary and check whether the dictionary exists or not.

marks={‘maths’:97,’science’:98,’history’:78}

del marks

print(marks) #Following Error is displayed :NameError: name ‘marks’ is not defined

7. Write a program create an empty dictionary capitals. Add key,value to the dictionary. When the user enters the key it should display the value; if the key does not exist, should exit the program.

Enter the state : AP

Capital of AP is Hyderabad

Enter the state : KA

Capital of KA is Bangalore

Enter the state : PP

Key does not exist

capitals={

“AP”:”Hyderabad”,

“TS”:”Hyderabad”,

“TN”:”Chennai”,

“KA”:”Bangalore”,

“WB”:”Calcutta”

}

capitals[“MH”]=”Mumbai”                 #adding

capitals[“WB”]=”Kolkatta”               #modifying

while True:

x=input(“Enter the state : “)

if(x in capitals):           #Checking whether the key exist in the dictionary or not

print(“Capital of {} is {} “.format(x,capitals[x]))

else:

print(“Key does not exist”)

break

8. Write a python program to remove the key from dictionary.

Initial dictionary {‘d’: 4, ‘c’: 3, ‘a’: 1, ‘b’: 2}

Enter the key to delete(a-d):c

Updated Dictionary : {‘d’: 4, ‘a’: 1, ‘b’: 2}

Enter the key to delete(a-d):t

Key not found!

d = {‘a’:1,’b’:2,’c’:3,’d’:4}

print(“Initial dictionary : “,d)

key=input(“Enter the key to delete(a-d):”)

if key in d:

del d[key]

print(“Updated Dictionary :”,d)

else:

print(“Key not found!”)

 

9. Write a program to update dictionary d1 with d2.
   Eg: d1={‘a’:1,’b’:2,’c’:3}
   d2={‘e’:4,’f’:5}

d1={‘a’:1,’b’:2,’c’:3}

d2={‘e’:4,’f’:5}

d1.update(d2)

print(“Dictionary after update : “,d1)

 

10. Write a program to Generate a Dictionary that Contains Numbers (between 1 and n). Take value n from the user and print the number and its square.

Enter a number:5

{1: 1, 2: 4, 3: 9, 4: 16, 5: 25}

n=int(input(“Enter a number:”))

d={x:x*x for x in range(1,n+1)}

print(d)

11. Write a program to sum all the values in a dictionary d={‘A’:101,’B’:40,’C’:976,’D’:2}

d={‘A’:101,’B’:40,’C’:976,’D’:2}

print(“Total sum of values in the dictionary is {}”.format(sum(d.values())))

 

12.Create a dictionary marks={‘maths’:97,’science’:98,’history’:78}. Print keys and values.

marks={‘maths’:97,’science’:98,’history’:78}

for subject,marks in marks.items():

print (subject,marks)