Label, title, and axis names in Matplotlib - Mini Project: Build & Apply

Label, title, and axis names

📖 Scenario: You are analyzing monthly sales data for a small store. You want to create a simple line chart to show how sales changed over the first six months of the year.

🎯 Goal: Create a line chart using matplotlib with proper labels for the x-axis and y-axis, and add a title to the chart.

📋 What You'll Learn

Create a list called months with the values: 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun'

Create a list called sales with the values: 250, 300, 280, 350, 400, 420

Use plt.plot() to create a line chart with months on the x-axis and sales on the y-axis

Add the x-axis label 'Month' using plt.xlabel()

Add the y-axis label 'Sales' using plt.ylabel()

Add the chart title 'Monthly Sales Data' using plt.title()

Display the chart using plt.show()

💡 Why This Matters

🌍 Real World

Labeling charts clearly helps people understand data trends quickly, such as sales over months or temperatures over days.

💼 Career

Data scientists and analysts often create charts with clear labels and titles to communicate insights effectively to teams and clients.

1

Create the data lists

Create a list called months with these exact values: 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun'. Also create a list called sales with these exact values: 250, 300, 280, 350, 400, 420.

Matplotlib

# Create the lists months and sales with the exact values
# Your code here

Hint

Use square brackets [] to create lists. Separate items with commas.

2

Import matplotlib and prepare to plot

Import matplotlib.pyplot as plt to prepare for plotting the data.

Matplotlib

months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun']
sales = [250, 300, 280, 350, 400, 420]
# Import matplotlib.pyplot as plt
# Your code here

Hint

Use import matplotlib.pyplot as plt to import the plotting library.

3

Create the line chart with labels and title

Use plt.plot() with months and sales to create the line chart. Then add the x-axis label 'Month' with plt.xlabel(), the y-axis label 'Sales' with plt.ylabel(), and the chart title 'Monthly Sales Data' with plt.title().

Matplotlib

import matplotlib.pyplot as plt

months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun']
sales = [250, 300, 280, 350, 400, 420]
# Plot the line chart and add labels and title
# Your code here

Hint

Use plt.plot(x, y) to create the line chart. Use plt.xlabel(), plt.ylabel(), and plt.title() to add labels and title.

4

Display the chart

Use plt.show() to display the chart with the labels and title.

Matplotlib

import matplotlib.pyplot as plt

months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun']
sales = [250, 300, 280, 350, 400, 420]

plt.plot(months, sales)
plt.xlabel('Month')
plt.ylabel('Sales')
plt.title('Monthly Sales Data')
# Display the chart
# Your code here

Hint

Use plt.show() to open the window with the chart.

Practice

1. Which matplotlib function is used to add a title to a plot?

easy

A. plt.label()

B. plt.title()

C. plt.name()

D. plt.head()

Solution

1. Step 1: Understand the purpose of each function

   plt.title() is designed to add a title to the plot, while the others do not exist or serve this purpose.

2. Step 2: Confirm the correct function for title

   The function plt.title() correctly adds a title to the plot.

3. Final Answer:

   plt.title() -> Option B

4. Quick Check:

   Title function = plt.title() [OK]

Hint: Title your plot with plt.title() for clarity [OK]

Common Mistakes:

• Using plt.label() instead of plt.title()
• Confusing axis labels with title
• Trying plt.name() which doesn't exist

2. Which of the following is the correct syntax to label the x-axis as 'Time (s)' in matplotlib?

easy

A. plt.axislabel('Time (s)')

B. plt.xaxis('Time (s)')

C. plt.labelx('Time (s)')

D. plt.xlabel('Time (s)')

Solution

1. Step 1: Recall the correct function for x-axis label

   The function to label the x-axis is plt.xlabel().

2. Step 2: Check syntax correctness

   plt.xlabel('Time (s)') uses the correct function and syntax: plt.xlabel('Time (s)').

3. Final Answer:

   plt.xlabel('Time (s)') -> Option D

4. Quick Check:

   X-axis label = plt.xlabel() [OK]

Hint: Use plt.xlabel() to name the x-axis quickly [OK]

Common Mistakes:

• Using plt.xaxis() which does not label axis
• Trying plt.labelx() which is invalid
• Confusing axis label with axis limits

3. What will be the output of the following code?

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.title('Sales Over Time')
plt.xlabel('Month')
plt.ylabel('Sales')
plt.show()

medium

A. A plot with title but no axis labels

B. A plot with no title and no axis labels

C. A plot with title 'Sales Over Time', x-axis labeled 'Month', and y-axis labeled 'Sales'

D. A plot with axis labels but no title

Solution

1. Step 1: Analyze the code for title and labels

   The code uses plt.title('Sales Over Time'), plt.xlabel('Month'), and plt.ylabel('Sales') to add title and axis labels.

2. Step 2: Understand the plot output

   The plot will display the line graph with the specified title and axis labels visible.

3. Final Answer:

   A plot with title 'Sales Over Time', x-axis labeled 'Month', and y-axis labeled 'Sales' -> Option C

4. Quick Check:

   Title and labels set = A plot with title 'Sales Over Time', x-axis labeled 'Month', and y-axis labeled 'Sales' [OK]

Hint: Check plt.title(), plt.xlabel(), plt.ylabel() for labels [OK]

Common Mistakes:

• Assuming labels won't show without plt.legend()
• Forgetting plt.show() to display plot
• Confusing axis labels with tick labels

4. Identify the error in this code snippet:

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [3, 2, 1])
plt.title = 'My Plot'
plt.xlabel('X Axis')
plt.ylabel('Y Axis')
plt.show()

medium

A. Incorrect assignment to plt.title instead of calling plt.title()

B. plt.xlabel() is missing parentheses

C. plt.plot() has wrong data format

D. plt.show() is missing

Solution

1. Step 1: Check how title is set

   The code uses plt.title = 'My Plot', which assigns a string to the function name, breaking it.

2. Step 2: Correct way to set title

   The correct syntax is to call the function: plt.title('My Plot').

3. Final Answer:

   Incorrect assignment to plt.title instead of calling plt.title() -> Option A

4. Quick Check:

   Title must be set by plt.title() function call [OK]

Hint: Use plt.title('text'), not plt.title = 'text' [OK]

Common Mistakes:

• Assigning string to plt.title instead of calling it
• Forgetting parentheses on function calls
• Confusing plt.title with plt.xlabel

5. You want to create a plot with the title 'Temperature Trends', x-axis labeled 'Day', and y-axis labeled 'Temperature (°C)'. Which code snippet correctly does this and also sets the font size of the title to 16?

hard

A. plt.title('Temperature Trends', fontsize=16)\nplt.xlabel('Day')\nplt.ylabel('Temperature (°C)')

B. plt.title('Temperature Trends')\nplt.xlabel('Day', fontsize=16)\nplt.ylabel('Temperature (°C)')

C. plt.title('Temperature Trends', size=16)\nplt.xlabel('Day')\nplt.ylabel('Temperature (°C)')

D. plt.title('Temperature Trends')\nplt.xlabel('Day')\nplt.ylabel('Temperature (°C)', fontsize=16)

Solution

1. Step 1: Identify how to set title font size

   The fontsize parameter in plt.title() sets the title font size correctly.

2. Step 2: Check axis labels and font size

   Only the title should have font size 16; axis labels do not need it here.

3. Final Answer:

   plt.title('Temperature Trends', fontsize=16) plt.xlabel('Day') plt.ylabel('Temperature (°C)') -> Option A

4. Quick Check:

   Title font size set by fontsize=16 in plt.title() [OK]

Hint: Use fontsize=16 inside plt.title() to resize title text [OK]

Common Mistakes:

• Using size=16 instead of fontsize=16
• Setting fontsize on axis labels instead of title
• Forgetting to call plt.title() as a function