np.count_nonzero() for counting in NumPy - Mini Project: Build & Apply

Counting Non-Zero Elements with np.count_nonzero()

📖 Scenario: Imagine you work in a store that tracks daily sales of different products. Some days, some products sell zero items. You want to find out how many products sold at least one item each day.

🎯 Goal: You will create a numpy array representing daily sales, then use np.count_nonzero() to count how many products sold more than zero items each day.

📋 What You'll Learn

Create a numpy array called daily_sales with the exact values given.

Create a variable called day_index to select a specific day.

Use np.count_nonzero() to count non-zero sales for the selected day.

Print the count of products sold on that day.

💡 Why This Matters

🌍 Real World

Stores and businesses often track sales data daily. Counting how many products sold helps understand customer demand and stock management.

💼 Career

Data analysts and scientists use numpy functions like <code>np.count_nonzero()</code> to quickly analyze datasets and extract useful insights.

1

Create the daily sales data

Create a numpy array called daily_sales with these exact values: [[3, 0, 5, 0], [0, 2, 0, 1], [4, 0, 0, 0]]. This array represents sales of 4 products over 3 days.

NumPy

import numpy as np
# Create the numpy array daily_sales with the given values
# Your code here

Need a hint?

Use np.array() and type the exact nested list of sales numbers.

2

Select the day to analyze

Create a variable called day_index and set it to 1 to select the second day (indexing starts at 0).

NumPy

import numpy as np

daily_sales = np.array([[3, 0, 5, 0], [0, 2, 0, 1], [4, 0, 0, 0]])
# Create day_index variable and set it to 1
# Your code here

Need a hint?

Remember, Python counts from zero, so the second day is index 1.

3

Count products sold on the selected day

Use np.count_nonzero() on daily_sales[day_index] to count how many products sold more than zero items on that day. Store the result in a variable called products_sold.

NumPy

import numpy as np

daily_sales = np.array([[3, 0, 5, 0], [0, 2, 0, 1], [4, 0, 0, 0]])
day_index = 1
# Use np.count_nonzero() on daily_sales[day_index] and save to products_sold
# Your code here

Need a hint?

Pass the selected day's sales array to np.count_nonzero() to count non-zero values.

4

Print the count of products sold

Print the value of products_sold to show how many products sold on the selected day.

NumPy

import numpy as np

daily_sales = np.array([[3, 0, 5, 0], [0, 2, 0, 1], [4, 0, 0, 0]])
day_index = 1
products_sold = np.count_nonzero(daily_sales[day_index])
# Print products_sold
# Your code here

Need a hint?

Use print(products_sold) to display the count.