Labels, titles, and legends in Data Analysis Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a title to the plot.

Data Analysis Python

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.[1]("My Plot Title")
plt.show()

Drag options to blanks, or click blank then click option'

Atitle

Bxlabel

Clegend

Dylabel

Attempts:

3 left

💡 Hint

Common Mistakes

Using xlabel or ylabel instead of title.

Trying to use legend to set the title.

The title function adds a title to the plot.

2fill in blank

medium

Complete the code to add a label to the x-axis.

Data Analysis Python

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.[1]("Time (seconds)")
plt.show()

Drag options to blanks, or click blank then click option'

Atitle

Blegend

Cylabel

Dxlabel

Attempts:

3 left

💡 Hint

Common Mistakes

Using ylabel instead of xlabel.

Trying to set the label with title or legend.

The xlabel function adds a label to the x-axis.

3fill in blank

hard

Fix the error in the code to add a legend to the plot.

Data Analysis Python

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6], label='Line 1')
plt.[1]()
plt.show()

Drag options to blanks, or click blank then click option'

Alegends

Blabel

Clegend

Dlegend_show

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'legends' instead of 'legend'.

Trying to call 'label()' to show the legend.

The correct function to show the legend is legend().

4fill in blank

hard

Fill both blanks to add labels to both axes.

Data Analysis Python

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.[1]("Days")
plt.[2]("Sales")
plt.show()

Drag options to blanks, or click blank then click option'

Axlabel

Btitle

Cylabel

Dlegend

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping xlabel and ylabel.

Using title or legend instead of axis labels.

xlabel sets the label for the x-axis, and ylabel sets the label for the y-axis.

5fill in blank

hard

Fill all three blanks to add a title, x-axis label, and legend to the plot.

Data Analysis Python

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6], label='Revenue')
plt.[1]("Monthly Revenue")
plt.[2]("Month")
plt.[3]()

Drag options to blanks, or click blank then click option'

Axlabel

Blegend

Ctitle

Dylabel

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up title and xlabel.

Forgetting parentheses on legend.

Using ylabel instead of xlabel.

title adds the plot title, xlabel labels the x-axis, and legend() shows the legend.

Practice

1. What is the main purpose of adding a title to a chart in data visualization?

easy

A. To give the chart a clear heading that explains what it shows

B. To label the x-axis with numbers

C. To add colors to the chart

D. To describe the data source

Solution

1. Step 1: Understand the role of a title in charts

   A title provides a clear heading that tells the viewer what the chart is about.

2. Step 2: Compare options with the title's purpose

   Only To give the chart a clear heading that explains what it shows correctly describes the purpose of a title as a clear heading.

3. Final Answer:

   To give the chart a clear heading that explains what it shows -> Option A

4. Quick Check:

   Title = Clear heading [OK]

Hint: Titles are headings that explain the whole chart [OK]

Common Mistakes:

• Confusing titles with axis labels
• Thinking titles add colors
• Mixing titles with legends

2. Which of the following is the correct way to add a legend to a Matplotlib plot in Python?

easy

A. plt.xlabel('Legend')

B. plt.title('Legend')

C. plt.legend()

D. plt.legend('show')

Solution

1. Step 1: Recall the Matplotlib function for legends

   The function plt.legend() adds a legend to the plot.

2. Step 2: Check other options for correctness

   Options A and B set x-axis label and title, not legend. plt.legend('show') uses incorrect syntax.

3. Final Answer:

   plt.legend() -> Option C

4. Quick Check:

   Legend function = plt.legend() [OK]

Hint: Use plt.legend() to show legends in Matplotlib [OK]

Common Mistakes:

• Using plt.title() to add legend
• Passing strings inside plt.legend() incorrectly
• Confusing xlabel with legend

3. What will be the output of this code snippet?

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

medium

A. A plot with two lines, a title, axis labels, and a legend showing 'Line 1' and 'Line 2'

B. A plot with no title and no legend

C. A plot with only one line and no labels

D. An error because legend labels are missing

Solution

1. Step 1: Analyze the plot commands

   Two lines are plotted with labels 'Line 1' and 'Line 2'. Title and axis labels are set.

2. Step 2: Understand legend and show functions

   Calling plt.legend() displays the legend with the given labels. plt.show() displays the plot.

3. Final Answer:

   A plot with two lines, a title, axis labels, and a legend showing 'Line 1' and 'Line 2' -> Option A

4. Quick Check:

   Legend and labels appear correctly [OK]

Hint: Labels in plot() + plt.legend() show legends automatically [OK]

Common Mistakes:

• Forgetting to call plt.legend()
• Assuming legend appears without labels
• Confusing axis labels with legend

4. Identify the error in this code that prevents the legend from showing:

import matplotlib.pyplot as plt
plt.plot([1, 2, 3])
plt.plot([3, 2, 1])
plt.legend()
plt.show()

medium

A. plt.legend() is called before plt.plot()

B. Missing labels in plot() calls for legend

C. plt.show() is missing

D. plt.title() is required for legend

Solution

1. Step 1: Check plot() calls for labels

   Both plot calls lack the label argument, so legend has no text to display.

2. Step 2: Verify legend and show usage

   Calling plt.legend() without labels results in an empty legend. plt.show() is present and plt.title() is not required.

3. Final Answer:

   Missing labels in plot() calls for legend -> Option B

4. Quick Check:

   Labels needed for legend [OK]

Hint: Add label='name' in plot() to show legend [OK]

Common Mistakes:

• Calling plt.legend() before plot()
• Thinking plt.title() affects legend
• Forgetting to call plt.show()

5. You have a DataFrame with sales data for two products over 3 months. You want to plot both lines on the same chart with a title, axis labels, and a legend. Which code snippet correctly adds all these elements?

import pandas as pd
import matplotlib.pyplot as plt

data = {'Month': ['Jan', 'Feb', 'Mar'], 'ProductA': [100, 120, 130], 'ProductB': [90, 110, 115]}
df = pd.DataFrame(data)

# Which code below is correct?

A: plt.plot(df['Month'], df['ProductA'], label='Product A')
   plt.plot(df['Month'], df['ProductB'], label='Product B')
   plt.title('Sales Over Months')
   plt.xlabel('Month')
   plt.ylabel('Sales')
   plt.legend()
   plt.show()

B: plt.plot(df['ProductA'], df['Month'], label='Product A')
   plt.plot(df['ProductB'], df['Month'], label='Product B')
   plt.title('Sales Over Months')
   plt.xlabel('Sales')
   plt.ylabel('Month')
   plt.legend()
   plt.show()

C: plt.plot(df['Month'], df['ProductA'])
   plt.plot(df['Month'], df['ProductB'])
   plt.title('Sales Over Months')
   plt.xlabel('Month')
   plt.ylabel('Sales')
   plt.show()

D: plt.plot(df['Month'], df['ProductA'], label='Product A')
   plt.plot(df['Month'], df['ProductB'], label='Product B')
   plt.xlabel('Month')
   plt.ylabel('Sales')
   plt.show()

hard

A. Missing title and legend, so incomplete chart

B. Swaps x and y axes and labels, causing incorrect plot

C. Missing legend call, so no legend shown

D. Correctly plots both products with labels, title, axis labels, and legend

Solution

1. Step 1: Check axis data and labels in each option

   Correctly plots both products with labels, title, axis labels, and legend uses Month on x-axis and sales on y-axis correctly with labels and title.

2. Step 2: Verify legend and title presence

   Correctly plots both products with labels, title, axis labels, and legend includes label in plot calls and calls plt.legend() and plt.title(). Others miss legend or swap axes.

3. Final Answer:

   Correctly plots both products with labels, title, axis labels, and legend -> Option D

4. Quick Check:

   Labels + legend + title = Correctly plots both products with labels, title, axis labels, and legend [OK]

Hint: Match x, y data and add labels + legend + title [OK]

Common Mistakes:

• Swapping x and y axes
• Forgetting plt.legend() call
• Missing title or axis labels