np.cumsum() for cumulative sum in NumPy - Mini Project: Build & Apply

Calculate Cumulative Sum Using np.cumsum()

📖 Scenario: Imagine you have daily sales numbers for a small shop. You want to see how sales add up day by day to understand the total sales over time.

🎯 Goal: You will create a list of daily sales, then use np.cumsum() to find the running total of sales each day.

📋 What You'll Learn

Create a numpy array called daily_sales with exact values: 5, 10, 7, 3, 8

Create a variable called cumulative_sales that stores the cumulative sum of daily_sales using np.cumsum()

Print the cumulative_sales array

💡 Why This Matters

🌍 Real World

Cumulative sums are used in finance to track total earnings, in health to track total steps walked, and in sales to track total revenue over time.

💼 Career

Data analysts and scientists often use cumulative sums to understand trends and totals in datasets, making this a key skill for reporting and decision-making.

1

Create the daily sales data

Import numpy as np and create a numpy array called daily_sales with these exact values: 5, 10, 7, 3, 8

NumPy

import numpy as np
# Create the numpy array daily_sales with values 5, 10, 7, 3, 8
# Your code here

Need a hint?

Use np.array() to create the array with the exact numbers inside square brackets.

2

Calculate cumulative sales

Create a variable called cumulative_sales and set it to the cumulative sum of daily_sales using np.cumsum()

NumPy

import numpy as np
daily_sales = np.array([5, 10, 7, 3, 8])
# Calculate cumulative_sales using np.cumsum on daily_sales
# Your code here

Need a hint?

Use np.cumsum() and pass daily_sales inside the parentheses.

3

Print the cumulative sales

Write a print statement to display the cumulative_sales array

NumPy

import numpy as np
daily_sales = np.array([5, 10, 7, 3, 8])
cumulative_sales = np.cumsum(daily_sales)
# Print the cumulative_sales array
# Your code here

Need a hint?

Use print(cumulative_sales) to show the running totals.

4

Explain the result

Add a print statement that explains the output by printing: 'Cumulative sales show total sales up to each day.'

NumPy

import numpy as np
daily_sales = np.array([5, 10, 7, 3, 8])
cumulative_sales = np.cumsum(daily_sales)
print(cumulative_sales)
# Print explanation text
# Your code here

Need a hint?

Use print() with the exact text inside quotes.