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Dictionaries in Python:
In Python, a dictionary dict is a one-to-one mapping; it includes a set of (key, value) pairs, with each key mapped to a value. It exemplifies a hash map or hash table (from Computer Science).
Each key denotes a value and is separated by a colon (:).
Curly brackets are used to define a dictionary. The value to the left of the colon is known as the key, while the value to the right of the colon is known as the value. A comma separates each (key, value) pair.
Example:
Example1:
Input:
Enter some random key = aplustopper Enter some random value of integer type = 2451
Output:
The dictionary after adding the key = aplustopper and value element = 2451 is :
{'aplustopper': 2451}Example2:
Input:
Enter some random key = 752 Enter some random value of integer type = 251
Output:
The dictionary after adding the key = 752 and value element = 251 is :
{752: 251}Example3:
Input:
Enter some random key = 234 Enter some random value of string type = btechgeeks
Output:
The dictionary after adding the key = 234 and value element = btechgeeks is :
{234: 'btechgeeks'}Program to Add a Key , Value Pair to the Dictionary
There are several ways to add a key, value pair to the dictionary some of them are:
Method #1:Using update() function (User input)
Approach:
- Give the key , value as user input and store them in two separate variables.
- Declare a dictionary and set its initial value to empty using {} or dict().
- To add the key-value pair to the dictionary, use the update() function.
- The Modified dictionary is printed.
- Exit of program.
i)Key of string datatype and value as integer datatype
Below is the implementation:
# given some random key
keyelement = input("Enter some random key = ")
# given some random value of int datatype
valueelement = int(input("Enter some random value of integer type = "))
# Declare a dictionary and set its initial value to empty using {} or dict()
sampledictionary = {}
# To add the key-value pair to the dictionary, use the update() function.
sampledictionary.update({keyelement: valueelement})
# The Modified dictionary is printed
print("The dictionary after adding the key =", keyelement,
"and value element =", valueelement, " is : ")
print(sampledictionary)
Output:
Enter some random key = btechgeeks
Enter some random value of integer type = 2841
The dictionary after adding the key = btechgeeks and value element = 2841 is :
{'btechgeeks': 2841}ii)Key of integer datatype and value as integer datatype
# given some random key
keyelement = int(input("Enter some random key = "))
# given some random value of int datatype
valueelement = int(input("Enter some random value of integer type = "))
# Declare a dictionary and set its initial value to empty using {} or dict()
sampledictionary = {}
# To add the key-value pair to the dictionary, use the update() function.
sampledictionary.update({keyelement: valueelement})
# The Modified dictionary is printed
print("The dictionary after adding the key =", keyelement,
"and value element =", valueelement, " is : ")
print(sampledictionary)
Output:
Enter some random key = 752
Enter some random value of integer type = 251
The dictionary after adding the key = 752 and value element = 251 is :
{752: 251}
iii)Key of integer datatype and value as string datatype
# given some random key
keyelement = int(input("Enter some random key = "))
# given some random value of string datatype
valueelement = input("Enter some random value of string type = ")
# Declare a dictionary and set its initial value to empty using {} or dict()
sampledictionary = {}
# To add the key-value pair to the dictionary, use the update() function.
sampledictionary.update({keyelement: valueelement})
# The Modified dictionary is printed
print("The dictionary after adding the key =", keyelement,
"and value element =", valueelement, " is : ")
print(sampledictionary)
Output:
Enter some random key = 234
Enter some random value of string type = btechgeeks
The dictionary after adding the key = 234 and value element = btechgeeks is :
{234: 'btechgeeks'}
Method #2:Using [] operator(User input)
Below is the implementation:
# given some random key
keyelement = input("Enter some random key = ")
# given some random value of integer datatype
valueelement = int(input("Enter some random value of integer type = "))
# Declare a dictionary and set its initial value to empty using {} or dict()
sampledictionary = {}
# using [] function
sampledictionary[keyelement] = valueelement
# The Modified dictionary is printed
print("The dictionary after adding the key =", keyelement,
"and value element =", valueelement, " is : ")
print(sampledictionary)
Output:
Enter some random key = aplustopper
Enter some random value of integer type = 2451
The dictionary after adding the key = aplustopper and value element = 2451 is :
{'aplustopper': 2451}Related Programs:
- Python Program to Swap the First and Last Value of a List
- Python Program to Generate a Dictionary that Contains Numbers (between 1 and n) in the Form (x, x*x).
- Python Program to Compute the Value of Euler’s Number ,Using the Formula: e = 1 + 1/1! + 1/2! + …… 1/n!
- Python program to Convert Kilometers to Miles and Vice Versa – A Step-By-Step Approach
