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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}
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