Counting with boolean arrays in NumPy - Mini Project: Build & Apply

Counting with boolean arrays

📖 Scenario: You work in a store and have a list of daily sales numbers. You want to find out how many days had sales above a certain target.

🎯 Goal: Build a small program that counts how many days had sales greater than a target using boolean arrays in NumPy.

📋 What You'll Learn

Use NumPy to create and work with arrays

Create a boolean array by comparing sales to a target

Count the number of True values in the boolean array

💡 Why This Matters

🌍 Real World

Stores and businesses often want to quickly find how many days or items meet a sales goal to track performance.

💼 Career

Data analysts and scientists use boolean arrays and counting techniques to summarize and analyze data efficiently.

1

Create the sales data array

Import NumPy as np and create a NumPy array called sales with these exact daily sales values: 100, 150, 90, 200, 130.

NumPy

# Import numpy as np and create the sales array
# Your code here

Need a hint?

Use np.array([...]) to create the array with the exact sales numbers.

2

Set the sales target

Create a variable called target and set it to the value 120.

NumPy

import numpy as np
sales = np.array([100, 150, 90, 200, 130])
# Create the target variable with value 120
# Your code here

Need a hint?

Just assign the number 120 to the variable target.

3

Create a boolean array for sales above target

Create a boolean NumPy array called above_target by comparing sales to target using the greater than operator >.

NumPy

import numpy as np
sales = np.array([100, 150, 90, 200, 130])
target = 120
# Create above_target array where sales are greater than target
# Your code here

Need a hint?

Use sales > target to get a boolean array.

4

Count and print the number of days above target

Use np.sum() on the above_target array to count how many days had sales above the target. Print the result.

NumPy

import numpy as np
sales = np.array([100, 150, 90, 200, 130])
target = 120
above_target = sales > target
# Print the count of days with sales above target
# Your code here

Need a hint?

Use np.sum(above_target) to count True values, then print it.