Log scale and symlog scale in Matplotlib - Mini Project: Build & Apply

Plotting with Log Scale and Symlog Scale in Matplotlib

📖 Scenario: You are working with a small business that tracks daily sales and wants to visualize the data clearly. Some days have very low sales, and some days have very high sales. To better understand the trends, you will create plots using log scale and symlog scale.

🎯 Goal: Build two line plots using matplotlib: one with a log scale on the y-axis and another with a symmetric log scale (symlog) on the y-axis. This will help visualize data that varies widely and includes zero or negative values.

📋 What You'll Learn

Create a list called days with values from 1 to 10.

Create a list called sales with these exact values: 0, 1, 10, 100, 1000, 10000, 100000, -10, -100, 0.

Create a variable called linthresh and set it to 20.

Plot days vs sales using plt.plot().

Set the y-axis scale to log using plt.yscale('log') for the first plot.

Create a second plot with y-axis scale set to symlog using plt.yscale('symlog', linthresh=linthresh).

Show both plots with plt.show().

💡 Why This Matters

🌍 Real World

Businesses often have data that varies a lot in size, like sales or website visits. Using log or symlog scales helps visualize such data clearly, especially when some values are zero or negative.

💼 Career

Data scientists and analysts use log and symlog scales to explore and present data effectively, making it easier to spot trends and outliers.

1

Create the data lists for days and sales

Create a list called days with values from 1 to 10, and a list called sales with these exact values: 0, 1, 10, 100, 1000, 10000, 100000, -10, -100, 0.

Matplotlib

# Create the days and sales lists
# Your code here

Need a hint?

Use square brackets to create lists. Make sure the values match exactly.

2

Set the linthresh variable for symlog scale

Create a variable called linthresh and set it to 20.

Matplotlib

days = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
sales = [0, 1, 10, 100, 1000, 10000, 100000, -10, -100, 0]
# Create linthresh variable and set it to 20
# Your code here

Need a hint?

Just assign the number 20 to the variable linthresh.

3

Plot days vs sales with log scale and symlog scale

Import matplotlib.pyplot as plt. Plot days vs sales using plt.plot(). Then set the y-axis scale to log using plt.yscale('log'). Create a new figure with plt.figure(), plot the same data again, and set the y-axis scale to symlog using plt.yscale('symlog', linthresh=linthresh).

Matplotlib

days = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
sales = [0, 1, 10, 100, 1000, 10000, 100000, -10, -100, 0]
linthresh = 20
# Import matplotlib.pyplot as plt
# Plot days vs sales with log scale
# Create new figure and plot days vs sales with symlog scale
# Your code here

Need a hint?

Remember to import matplotlib.pyplot as plt first. Use plt.plot() to draw the lines. Use plt.yscale() to set the scale.

4

Show the plots

Use plt.show() to display both plots.

Matplotlib

import matplotlib.pyplot as plt

days = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
sales = [0, 1, 10, 100, 1000, 10000, 100000, -10, -100, 0]
linthresh = 20

plt.plot(days, sales)
plt.yscale('log')

plt.figure()
plt.plot(days, sales)
plt.yscale('symlog', linthresh=linthresh)
# Show the plots
# Your code here

Need a hint?

Use plt.show() once after all plots are ready to display them.