Saving to PNG, SVG, PDF in Matplotlib - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to save the plot as a PNG file named 'plot.png'.

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.[1]('plot.png')

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

Ashow

Bsavefig

Cplot

Dfigure

Attempts:

3 left

💡 Hint

Common Mistakes

Using plt.show() instead of plt.savefig()

Trying to save without calling savefig

Using plt.plot() to save the file

The savefig function saves the current figure to a file. Here, it saves as 'plot.png'.

2fill in blank

medium

Complete the code to save the plot as an SVG file named 'image.svg'.

Matplotlib

import matplotlib.pyplot as plt
plt.plot([10, 20, 30], [1, 4, 9])
plt.[1]('image.svg')

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

Asavefig

Bdraw

Cshow

Dfigure

Attempts:

3 left

💡 Hint

Common Mistakes

Using plt.show() instead of plt.savefig()

Not specifying the file extension

Using plt.draw() which only updates the plot

Use savefig to save the plot as an SVG file by specifying the filename with '.svg' extension.

3fill in blank

hard

Fix the error in the code to save the plot as a PDF file named 'chart.pdf'.

Matplotlib

import matplotlib.pyplot as plt
plt.plot([5, 6, 7], [8, 9, 10])
plt.[1]('chart.pdf')

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

Asave

Bsave_plot

Csavefig

Dsave_image

Attempts:

3 left

💡 Hint

Common Mistakes

Using plt.save() which does not exist

Using plt.savefig() but misspelling it

Trying to save without calling any function

The correct function to save a figure is savefig, not save.

4fill in blank

hard

Fill both blanks to save the plot as a PNG file with 300 dpi resolution.

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 3, 5], [2, 4, 6])
plt.[1]('high_res.png', dpi=[2])

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

Asavefig

Bshow

C300

D100

Attempts:

3 left

💡 Hint

Common Mistakes

Using plt.show() instead of plt.savefig()

Setting dpi to a low value like 100

Not specifying dpi at all

Use savefig to save the plot and set dpi=300 for high resolution.

5fill in blank

hard

Fill all three blanks to save the plot as a PDF file with transparent background and tight bounding box.

Matplotlib

import matplotlib.pyplot as plt
plt.plot([2, 4, 6], [1, 3, 5])
plt.[1]('output.pdf', transparent=[2], bbox_inches=[3])

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

Asavefig

BTrue

C'tight'

DFalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using plt.show() instead of plt.savefig()

Setting transparent to False

Not using bbox_inches='tight'

Use savefig with transparent=True and bbox_inches='tight' to save a PDF with a transparent background and no extra whitespace.

Practice

1. What does the plt.savefig() function do in matplotlib?

easy

A. It displays the plot on the screen.

B. It saves the current plot to a file in a specified format.

C. It clears the current plot.

D. It creates a new figure for plotting.

Solution

1. Step 1: Understand the purpose of plt.savefig()

   This function is used to save the current figure to a file on your computer.

2. Step 2: Differentiate from other functions

   Functions like plt.show() display the plot, but do not save it. plt.savefig() specifically saves the plot as an image file.

3. Final Answer:

   It saves the current plot to a file in a specified format. -> Option B

4. Quick Check:

   Save plot = plt.savefig() [OK]

Hint: Remember: savefig saves, show displays [OK]

Common Mistakes:

• Confusing plt.savefig() with plt.show()
• Thinking savefig displays the plot
• Using savefig after plt.show() causing empty files

2. Which of the following is the correct syntax to save a plot as a PDF file named 'chart.pdf'?

easy

A. plt.savefig('chart.pdf')

B. plt.save('chart.pdf')

C. plt.savefig('chart.pdf', format='png')

D. plt.savefig(chart.pdf)

Solution

1. Step 1: Identify the correct function name

   The correct function to save a plot is plt.savefig().

2. Step 2: Use correct string syntax for filename

   The filename must be a string, so it should be enclosed in quotes: 'chart.pdf'.

3. Final Answer:

   plt.savefig('chart.pdf') -> Option A

4. Quick Check:

   Correct function and string filename = plt.savefig('chart.pdf') [OK]

Hint: Use plt.savefig('filename.ext') with quotes [OK]

Common Mistakes:

• Omitting quotes around filename
• Using plt.save() instead of plt.savefig()
• Passing filename without quotes causing syntax error

3. What will be the output file format if you run this code?

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.savefig('output_image.svg')
plt.close()

medium

A. SVG vector graphic file

B. PNG image file

C. PDF document file

D. JPEG image file

Solution

1. Step 1: Check the filename extension in savefig

   The filename is 'output_image.svg', which ends with '.svg'.

2. Step 2: Understand file format selection by extension

   Matplotlib saves the plot in the format matching the file extension. '.svg' means it saves as an SVG vector graphic.

3. Final Answer:

   SVG vector graphic file -> Option A

4. Quick Check:

   File extension '.svg' = SVG format [OK]

Hint: File extension decides format: .svg means SVG file [OK]

Common Mistakes:

• Assuming default PNG without checking extension
• Confusing SVG with PDF format
• Not saving before closing causing empty files

4. Identify the error in this code snippet that tries to save a plot as a PNG file:

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

medium

A. plt.savefig() requires an additional argument for format.

B. The filename extension '.png' is incorrect for saving images.

C. plt.plot() is missing required arguments.

D. The plot is saved after plt.show(), which may save a blank image.

Solution

1. Step 1: Understand the order of plt.show() and plt.savefig()

   Calling plt.show() displays and clears the figure by default.

2. Step 2: Identify consequence of saving after show()

   Saving after plt.show() often results in an empty or blank image file.

3. Final Answer:

   The plot is saved after plt.show(), which may save a blank image. -> Option D

4. Quick Check:

   Save before show to avoid blank files [OK]

Hint: Always savefig before show() to keep the plot [OK]

Common Mistakes:

• Saving after plt.show() causing empty files
• Thinking filename extension needs special format argument
• Assuming plt.plot() needs more arguments

5. You want to save the same plot in three formats: PNG, SVG, and PDF. Which code snippet correctly saves the plot in all three formats?

hard

A. plt.plot([1,2,3],[3,2,1])
plt.savefig('plot.png')
plt.savefig('plot.jpg')
plt.savefig('plot.pdf')

B. plt.plot([1,2,3],[3,2,1])
plt.savefig('plot')
plt.savefig('plot')
plt.savefig('plot')

C. plt.plot([1,2,3],[3,2,1])
plt.savefig('plot.png', format='png')
plt.savefig('plot.svg', format='svg')
plt.savefig('plot.pdf', format='pdf')

D. plt.plot([1,2,3],[3,2,1])
plt.save('plot.png')
plt.save('plot.svg')
plt.save('plot.pdf')

Solution

1. Step 1: Check function names and parameters

   The correct function is plt.savefig(). plt.plot([1,2,3],[3,2,1]) plt.save('plot.png') plt.save('plot.svg') plt.save('plot.pdf') uses plt.save(), which is invalid.

2. Step 2: Confirm saving with explicit format or extension

   plt.plot([1,2,3],[3,2,1]) plt.savefig('plot') plt.savefig('plot') plt.savefig('plot') uses filenames without extensions, so format is unclear. plt.plot([1,2,3],[3,2,1]) plt.savefig('plot.png') plt.savefig('plot.svg') plt.savefig('plot.pdf') relies on extensions only, which works but may be less explicit.

3. Step 3: Understand explicit format argument

   plt.plot([1,2,3],[3,2,1]) plt.savefig('plot.png', format='png') plt.savefig('plot.svg', format='svg') plt.savefig('plot.pdf', format='pdf') uses both filename and explicit format argument, ensuring correct file type saving.

4. Final Answer:

   Saves the plot in PNG, SVG, and PDF formats using explicit format arguments. -> Option C

5. Quick Check:

   Use plt.savefig(filename, format='ext') for clarity [OK]

Hint: Use plt.savefig with filename and format='ext' for multiple saves [OK]

Common Mistakes:

• Using plt.save() instead of plt.savefig()
• Saving without file extensions causing format errors
• Not specifying format when filename lacks extension