Figure size for publication in Matplotlib

Introduction

Setting the right figure size helps your charts look clear and professional when you add them to reports or papers.

When you want your plot to fit nicely in a printed report or journal.

When you need consistent sizes for multiple charts in a presentation.

When preparing images for online articles with specific size limits.

When you want to control the resolution and layout of your saved figures.

Syntax

Matplotlib

plt.figure(figsize=(width, height))

width and height are in inches.

Use this before creating your plot to set the size.

Examples

This creates a plot 6 inches wide and 4 inches tall.

Matplotlib

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

A square figure, useful for small charts or icons.

Matplotlib

plt.figure(figsize=(3, 3))
plt.bar(['A', 'B'], [10, 20])
plt.show()

A wide and short figure, good for timeline or trend lines.

Matplotlib

plt.figure(figsize=(8, 2))
plt.plot([0, 1, 2], [2, 3, 4])
plt.show()

Sample Program

This code sets the figure size to 5 inches wide and 3 inches tall, then plots a simple line chart with markers. This size is good for fitting into a publication column.

Matplotlib

import matplotlib.pyplot as plt

# Set figure size for publication
plt.figure(figsize=(5, 3))

# Create a simple line plot
x = [0, 1, 2, 3, 4]
y = [0, 1, 4, 9, 16]
plt.plot(x, y, marker='o')

# Add title and labels
plt.title('Sample Plot for Publication')
plt.xlabel('X axis')
plt.ylabel('Y axis')

# Show the plot
plt.show()

Important Notes

Figure size is measured in inches, not pixels.

When saving figures, use plt.savefig('filename.png', dpi=300) for high quality.

Adjusting figure size helps keep text and labels readable in your final output.

Summary

Use plt.figure(figsize=(width, height)) to set plot size in inches.

Choose sizes that fit your publication or presentation layout.

Combine figure size with resolution settings for best results.

Practice

1. What does the figsize parameter control in a matplotlib figure?

easy

A. The font size of the labels

B. The width and height of the figure in inches

C. The color of the figure background

D. The style of the plot lines

Solution

1. Step 1: Understand the role of figsize

   The figsize parameter sets the size of the entire figure in inches, controlling width and height.

2. Step 2: Differentiate from other parameters

   Other parameters like color or font size do not affect figure size but appearance details.

3. Final Answer:

   The width and height of the figure in inches -> Option B

4. Quick Check:

   Figure size = width and height in inches [OK]

Hint: Remember figsize sets width and height in inches [OK]

Common Mistakes:

• Confusing figsize with color or font size
• Thinking figsize controls plot line style
• Assuming figsize is in pixels

2. Which of the following is the correct way to set a figure size of 8 inches wide and 4 inches tall in matplotlib?

easy

A. plt.figure(size=[8, 4])

B. plt.figure(size=(8, 4))

C. plt.figure(width=8, height=4)

D. plt.figure(figsize=(8, 4))

Solution

1. Step 1: Recall correct parameter name and type

   The parameter to set figure size is figsize and it expects a tuple (width, height).

2. Step 2: Check syntax correctness

   plt.figure(figsize=(8, 4)) uses figsize=(8, 4) which is correct syntax. Using size causes TypeError (unexpected keyword). Using width=8, height=4 also causes TypeError (no such parameters).

3. Final Answer:

   plt.figure(figsize=(8, 4)) -> Option D

4. Quick Check:

   Use figsize=(width, height) tuple [OK]

Hint: Use figsize=(width, height) tuple in plt.figure() [OK]

Common Mistakes:

• Using 'size' instead of 'figsize'
• Using separate width and height parameters
• Forgetting parentheses around figsize values

3. What will be the size of the figure in inches after running this code?

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

medium

A. 6 inches wide and 3 inches tall

B. 3 inches wide and 6 inches tall

C. Default size (usually 6.4 x 4.8 inches)

D. Cannot determine without dpi

Solution

1. Step 1: Identify figsize parameter values

   The code sets figsize=(6, 3), which means width=6 inches and height=3 inches.

2. Step 2: Understand effect on figure size

   This directly sets the figure size regardless of dpi, so the figure will be 6 inches wide and 3 inches tall.

3. Final Answer:

   6 inches wide and 3 inches tall -> Option A

4. Quick Check:

   figsize=(6, 3) means width=6, height=3 inches [OK]

Hint: figsize=(width, height) sets exact figure size in inches [OK]

Common Mistakes:

• Swapping width and height values
• Thinking dpi affects figsize dimensions
• Assuming default size if figsize is set

4. Identify the error in this code that tries to set figure size:

import matplotlib.pyplot as plt
plt.figure(figsize=8, 4)
plt.plot([1, 2], [3, 4])
plt.show()

medium

A. No error, code runs fine

B. plt.plot syntax is incorrect

C. figsize should be a tuple, not two separate arguments

D. plt.show() is missing parentheses

Solution

1. Step 1: Check figsize parameter usage

   The code uses figsize=8, 4 which passes two separate arguments instead of a single tuple.

2. Step 2: Understand correct figsize syntax

   Correct syntax requires a tuple: figsize=(8, 4). Without parentheses, it causes a TypeError.

3. Final Answer:

   figsize should be a tuple, not two separate arguments -> Option C

4. Quick Check:

   figsize=(width, height) needs parentheses [OK]

Hint: Always use parentheses for figsize tuple [OK]

Common Mistakes:

• Passing figsize values without parentheses
• Confusing plt.plot syntax errors
• Forgetting plt.show() parentheses (not the case here)

5. You want to create a publication-ready plot with a width of 7 inches and height of 5 inches. You also want to save it as a PNG file with 300 dpi resolution. Which code snippet correctly sets the figure size and saves the plot?

hard

A. plt.figure(figsize=(7, 5))
plt.plot(data)
plt.savefig('plot.png', dpi=300)

B. plt.figure(size=(7, 5))
plt.plot(data)
plt.savefig('plot.png', dpi=300)

C. plt.figure(figsize=[7, 5])
plt.plot(data)
plt.savefig('plot.png')

D. plt.figure(figsize=(7, 5))
plt.plot(data)
plt.save('plot.png', dpi=300)

Solution

1. Step 1: Set figure size correctly

   Use figsize=(7, 5) tuple in plt.figure() to set width and height in inches.

2. Step 2: Save figure with correct dpi and function

   Use plt.savefig('plot.png', dpi=300) to save with 300 dpi resolution. plt.figure(size=(7, 5)) plt.plot(data) plt.savefig('plot.png', dpi=300) uses wrong parameter size. plt.figure(figsize=[7, 5]) plt.plot(data) plt.savefig('plot.png') misses dpi. plt.figure(figsize=(7, 5)) plt.plot(data) plt.save('plot.png', dpi=300) uses wrong function plt.save.

3. Final Answer:

   plt.figure(figsize=(7, 5)) plt.plot(data) plt.savefig('plot.png', dpi=300) -> Option A

4. Quick Check:

   figsize tuple + savefig with dpi=300 [OK]

Hint: Use figsize tuple and savefig with dpi for publication [OK]

Common Mistakes:

• Using 'size' instead of 'figsize'
• Forgetting dpi in savefig for quality
• Using plt.save instead of plt.savefig