Find the Sum of Dictionary Keys in Python

In this article, we will learn a python program to find the sum of dictionary keys.

Methods Used

The following are the various methods to accomplish this task ?

• Using for loop

• Using dict.keys() and sum() functions

• Using reduce() function

• Using items() function

Example

Assume we have taken an input dictionary containing some random key-value pairs. We will now find the sum of all the keys of an input dictionary using the above methods.

Input

inputDict = {4: 10, 1: 30, 10: 50, 2: 70, 8: 90}

Output

Sum of keys of an input dictionary: 25

In the above example, the sum of keys of an input dictionary is 4+1+10+2+8 = 25.

Method 1: Using For Loop

Algorithm (Steps)

Following are the Algorithms/steps to be followed to perform the desired task -.

• Create a variable to store the input dictionary.

• Print the input dictionary.

• Initialize a keysSum variable with 0 for the resultant storing sum of keys of an input dictionary.

• Use the for loop to traverse through the keys of an input dictionary.

• Use the + operator to add the current key to the keysSum variable.

• Print the resultant sum of keys of an input dictionary.

Example

The following program returns the sum of all the keys of an input dictionary using the for loop -

# input dictionary
inputDict = {4: 10, 1: 30, 10: 50, 2: 70, 8: 90}

# printing the input dictionary
print("Input Dictionary: ", inputDict)

# storing the sum of keys of the input dictionary
keysSum = 0

# traversing through the keys of an input dictionary
for k in inputDict:

   # adding the current key to keysSum variable
   keysSum += k

# printing the sum of keys of an input dictionary
print("Sum of keys of an input dictionary:", keysSum)

Output

On execution, the above program will generate the following output -

Input Dictionary: {4: 10, 1: 30, 10: 50, 2: 70, 8: 90}
Sum of keys of an input dictionary: 25

Method 2: Using dict.keys() and sum() functions

dict.keys() function ? provides a view object that displays a list of all the keys in the dictionary in order of insertion

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task -

• Use the dict.keys() function to get the keys of the input dictionary and convert them into a list using list() function(returns a list of an iterable).

• Get the sum of the dictionary keys using the sum() function(returns the sum of all items in an iterable).

• Print the resultant sum of all the keys of an input dictionary.

Example

The following program returns the sum of all the keys of an input dictionary using dict.keys() and sum() functions -

# input dictionary
inputDict = {4: 10, 1: 30, 10: 50, 2: 70, 8: 90}
print("Input Dictionary: ", inputDict)

# getting the keys of the input dictionary and converting them into the list

# and then getting the sum of dictionary keys
keysSum = sum(list(inputDict.keys()))
print("Sum of keys of an input dictionary:", keysSum)

Output

On execution, the above program will generate the following output -

Input Dictionary: {4: 10, 1: 30, 10: 50, 2: 70, 8: 90}
Sum of keys of an input dictionary: 25

Method 3: Using reduce( ) function

reduce() function

In Python, the reduce() function iterates through each item in a list or other iterable data type, returning a single value. It's in the functools library. This is more efficient than looping.

Syntax

reduce(function, iterable)

Lambda Function

Lambda Function, often known as an 'Anonymous Function,' is the same as a normal Python function except that it can be defined without a name. The def keyword is used to define normal functions, while the lambda keyword is used to define anonymous functions. They are, however, limited to a single line of expression. They, like regular functions, can accept several parameters.

Syntax

lambda arguments: expression

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task -

• Use the import keyword to import reduce function from functools module.

• Add the consecutive dictionary keys using the lambda function and reduce the size to make a single element(sum of all keys).

• Print the resultant sum of all the keys of an input dictionary.

Example

The following program returns the sum of all the keys of an input dictionary using reduce( ) function -

# importing reduce function from functools module
from functools import reduce
inputDict = {4: 10, 1: 30, 10: 50, 2: 70, 8: 90}
print("Input Dictionary: ", inputDict)

# Add the keys and reduce it to a single number(sum) using reduce() function
keysSum = reduce(lambda p, q: p + q, inputDict)
print("Sum of keys of an input dictionary:", keysSum)

Output

On execution, the above program will generate the following output -

Input Dictionary: {4: 10, 1: 30, 10: 50, 2: 70, 8: 90}
Sum of keys of an input dictionary: 25

Method 4: Using items() function

Use the dictionary.items() function to traverse through the tuples in a dictionary with the for loop.

The items() function returns a view object i.e, it contains the key-value pairs of the dictionary, as tuples in a list.

Example

The following program returns the sum of all the keys of an input dictionary using the items() function and for loop -

inputDict = {4: 10, 1: 30, 10: 50, 2: 70, 8: 90}
print("Input Dictionary: ", inputDict)

# storing the sum of keys of the input dictionary
keysSum = 0

# traversing through the keys, and values of an input dictionary
for key, value in inputDict.items():
   
   # adding the current key to keysSum variable
   keysSum += key
print("Sum of keys of an input dictionary:", keysSum)

Output

On execution, the above program will generate the following output -

Input Dictionary: {4: 10, 1: 30, 10: 50, 2: 70, 8: 90}
Sum of keys of an input dictionary: 25

Conclusion

In this article, we learned 4 different methods for computing the dictionary's total key's sum. We also learned how to add conditions to the iterable items using the lambda function and reduce.