Text annotations in Matplotlib - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a text annotation at coordinates (2, 3) on the plot.

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [1, 4, 9])
plt.[1](2, 3, 'Point')
plt.show()

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

Atitle

Blabel

Ctext

Dannotate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'annotate' instead of 'text' for simple text placement.

Trying to use 'label' which is not a matplotlib function.

Using 'title' which sets the plot title, not text at coordinates.

The text function adds text at specified coordinates on the plot.

2fill in blank

medium

Complete the code to add an annotation with an arrow pointing to (2, 4) with text 'Max'.

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [1, 4, 9])
plt.annotate('Max', xy=(2, 4), xytext=(3, 5), arrowprops=[1])
plt.show()

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

A{'arrowstyle': '->'}

B{'style': '->'}

C{'arrow': '->'}

D{'arrowstyle': '-->'}

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'style' instead of 'arrowstyle' as the key.

Using 'arrow' which is not a valid key.

Using '-->' which is not a recognized arrow style.

The arrowprops dictionary must include 'arrowstyle' to define the arrow style.

3fill in blank

hard

Fix the error in the code to correctly place an annotation with an arrow.

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [1, 4, 9])
plt.annotate('Peak', xy=(3, 9), xytext=(2, 7), arrowprops=[1])
plt.show()

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

A{'arrowstyle': '->'}

B'arrowstyle': '->'

C{'arrowstyle': '->', 'color': 'red'}

D{'arrow': '->'}

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a string instead of a dictionary for arrowprops.

Using an invalid key like 'arrow' instead of 'arrowstyle'.

Forgetting the braces around the dictionary.

The arrowprops argument must be a dictionary. Option A is missing braces, and D uses an invalid key.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps words to their lengths only if length is greater than 3.

Matplotlib

words = ['data', 'science', 'ai', 'ml']
lengths = {word: [1] for word in words if [2]

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

Alen(word)

Blen(word) > 3

Cword

Dword > 3

Attempts:

3 left

💡 Hint

Common Mistakes

Using the word itself as the value instead of its length.

Using the word in the condition instead of its length.

Using incorrect comparison operators.

The dictionary comprehension maps each word to its length using len(word). The condition filters words with length greater than 3 using len(word) > 3.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps uppercase words to their lengths if length is greater than 2.

Matplotlib

words = ['cat', 'dog', 'a', 'bird']
result = { [1]: [2] for w in words if [3] }

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

Aw.upper()

Blen(w)

Clen(w) > 2

Dw

Attempts:

3 left

💡 Hint

Common Mistakes

Using the original word as key instead of uppercase.

Using the word itself as value instead of length.

Incorrect condition for filtering.

The dictionary comprehension uses w.upper() as keys, len(w) as values, and filters words with length greater than 2.

Practice

1. What is the main purpose of adding text annotations in a matplotlib plot?

easy

A. To add labels or notes that explain or highlight data points

B. To change the color of the plot lines

C. To increase the size of the plot window

D. To save the plot as an image file

Solution

1. Step 1: Understand what text annotations do

   Text annotations add extra information like labels or notes on specific parts of a plot.

2. Step 2: Identify the correct purpose

   Changing colors or saving files are unrelated to annotations, which focus on explaining or highlighting data points.

3. Final Answer:

   To add labels or notes that explain or highlight data points -> Option A

4. Quick Check:

   Annotations = labels/notes [OK]

Hint: Annotations explain data points clearly on plots [OK]

Common Mistakes:

• Confusing annotations with plot styling
• Thinking annotations save or export plots
• Assuming annotations change plot size

2. Which of the following is the correct syntax to add a text annotation at point (2, 3) with the text 'Peak' in matplotlib?

easy

A. plt.annotate(xy=(2, 3), text='Peak')

B. plt.text('Peak', xy=(2, 3))

C. plt.annotate('Peak', xy=(2, 3))

D. plt.text(x=2, y=3, label='Peak')

Solution

1. Step 1: Recall the correct function and parameter order

   The function plt.annotate takes the text first, then the xy coordinate as a tuple.

2. Step 2: Check each option

   plt.annotate('Peak', xy=(2, 3)) uses plt.annotate('Peak', xy=(2, 3)) which is correct. Others misuse parameter names or functions.

3. Final Answer:

   plt.annotate('Peak', xy=(2, 3)) -> Option C

4. Quick Check:

   annotate(text, xy=point) = correct syntax [OK]

Hint: Use plt.annotate('text', xy=(x,y)) for annotations [OK]

Common Mistakes:

• Swapping text and xy parameters
• Using plt.text with wrong arguments
• Incorrect parameter names like label or text=

3. What will the following code display?

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.annotate('Max', xy=(3, 6), xytext=(2, 5), arrowprops=dict(facecolor='black'))
plt.show()

medium

A. A line plot with an annotation 'Max' at point (3,6) with an arrow pointing from (2,5)

B. A line plot with text 'Max' at (2,5) but no arrow

C. A line plot with an annotation 'Max' at (2,5) without arrow

D. Syntax error due to incorrect arrowprops usage

Solution

1. Step 1: Understand plt.annotate parameters

   xy is the point to annotate (3,6), xytext is where the text appears (2,5), arrowprops adds an arrow from text to point.

2. Step 2: Analyze the code output

   The plot shows a line, with 'Max' text at (2,5) and an arrow pointing to (3,6).

3. Final Answer:

   A line plot with an annotation 'Max' at point (3,6) with an arrow pointing from (2,5) -> Option A

4. Quick Check:

   annotate with xy, xytext, arrowprops = arrowed label [OK]

Hint: xy=point, xytext=text location, arrowprops=arrow [OK]

Common Mistakes:

• Confusing xy and xytext roles
• Expecting arrow without arrowprops
• Thinking arrowprops causes syntax error

4. Identify the error in this code snippet:

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.annotate('High', (3, 6), xytext=(2, 5), arrowprops='black')
plt.show()

medium

A. plt.plot arguments are incorrect

B. arrowprops should be a dictionary, not a string

C. The text 'High' should be passed as xytext

D. xytext parameter is missing

Solution

1. Step 1: Check arrowprops usage

   arrowprops must be a dictionary specifying arrow style, not a string.

2. Step 2: Verify other parameters

   xytext is present, text is first argument, plot args are correct.

3. Final Answer:

   arrowprops should be a dictionary, not a string -> Option B

4. Quick Check:

   arrowprops = dict(...) not string [OK]

Hint: arrowprops needs dict with arrow style, not string [OK]

Common Mistakes:

• Passing arrowprops as string
• Confusing text and xytext parameters
• Incorrect plot data format

5. You want to highlight the lowest point on a plot with an annotation that includes an arrow and custom text offset. Which code snippet correctly achieves this for data points x=[1,2,3], y=[5,3,6]?

hard

A. plt.annotate('Lowest', xy=(2, 3), xytext=(2, 3), arrowprops=dict(color='blue'))

B. plt.annotate('Lowest', xytext=(2, 3), xy=(1, 4), arrowprops='red')

C. plt.text('Lowest', xy=(2, 3), xytext=(1, 4), arrowprops=dict(facecolor='red'))

D. plt.annotate('Lowest', xy=(2, 3), xytext=(1, 4), arrowprops=dict(facecolor='red'))

Solution

1. Step 1: Identify the lowest point coordinates

   Lowest y is 3 at x=2, so xy=(2,3) is correct.

2. Step 2: Check annotation parameters

   xytext=(1,4) offsets text for clarity, arrowprops uses dict with facecolor for arrow color.

3. Step 3: Validate options

   plt.annotate('Lowest', xy=(2, 3), xytext=(1, 4), arrowprops=dict(facecolor='red')) matches correct syntax and logic. Others misuse parameters or functions.

4. Final Answer:

   plt.annotate('Lowest', xy=(2, 3), xytext=(1, 4), arrowprops=dict(facecolor='red')) -> Option D

5. Quick Check:

   Correct xy, xytext, arrowprops dict = plt.annotate('Lowest', xy=(2, 3), xytext=(1, 4), arrowprops=dict(facecolor='red')) [OK]

Hint: Use xy for point, xytext for label offset, arrowprops dict [OK]

Common Mistakes:

• Swapping xy and xytext
• Using plt.text instead of plt.annotate
• Passing arrowprops as string