Nested subplots with subfigures in Matplotlib - Step-by-Step Execution

Concept Flow - Nested subplots with subfigures

Create Figure

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Add Subfigure 1

→Add Subplots in Subfigure 1

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Add Subfigure 2

→Add Subplots in Subfigure 2

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Plot data in each subplot

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Show Figure with nested subplots

Start by creating a main figure, then add subfigures inside it. Each subfigure can have its own grid of subplots. Finally, plot data in each subplot and display the figure.

Execution Sample

Matplotlib

import matplotlib.pyplot as plt
fig = plt.figure()
subfigs = fig.subfigures(1, 2)
ax1 = subfigs[0].subplots(2, 1)
ax2 = subfigs[1].subplots(1, 2)
ax1[0].plot([1, 2], [3, 4])
plt.show()

This code creates a figure with two subfigures side by side. The first subfigure has two rows of subplots, the second has two columns. It plots a simple line in the first subplot.

Execution Table

Step	Action	Result/State	Notes
1	Create main figure	Figure object created	Empty figure ready
2	Add 2 subfigures horizontally	Two subfigure objects inside main figure	Subfigures split figure into left and right parts
3	Create 2-row subplots in left subfigure	Array of 2 Axes objects in left subfigure	Vertical stack of plots
4	Create 2-column subplots in right subfigure	Array of 2 Axes objects in right subfigure	Horizontal side-by-side plots
5	Plot line on first subplot of left subfigure	Line appears on ax1[0]	Data plotted on first subplot
6	Show figure	Window with nested subplots appears	All subplots visible with layout
7	End	Execution stops	All plotting done

💡 All subplots created and plotted, figure displayed, program ends

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	After Step 5	Final
fig	None	Figure object	Figure object	Figure object	Figure object	Figure object
subfigs	None	Array of 2 subfigures	Array of 2 subfigures	Array of 2 subfigures	Array of 2 subfigures	Array of 2 subfigures
ax1	None	None	Array of 2 Axes (vertical)	Array of 2 Axes (vertical)	Array of 2 Axes (vertical) with line on ax1[0]	Array of 2 Axes (vertical) with line on ax1[0]
ax2	None	None	None	Array of 2 Axes (horizontal)	Array of 2 Axes (horizontal)	Array of 2 Axes (horizontal)

Key Moments - 3 Insights

Why do we create subfigures before subplots?

Subfigures act like containers inside the main figure. We add subplots inside these containers to organize plots in groups. See execution_table steps 2 and 3.

Can subfigures have different subplot layouts?

Yes, each subfigure can have its own grid size and shape. For example, left subfigure has 2 rows, right subfigure has 2 columns (execution_table steps 3 and 4).

What happens if we plot before creating subplots?

You need Axes objects to plot on. Without subplots, there is no place to draw. So plotting happens after subplots are created (step 5).

Visual Quiz - 3 Questions

Look at the variable_tracker table. What is the value of 'ax1' after Step 3?

A Array of 2 Axes arranged vertically

B Array of 2 Axes arranged horizontally

C None

D Single Axes object

💡 Hint

Check the 'ax1' row under 'After Step 3' column in variable_tracker

According to the execution_table, at which step do we add subplots to the right subfigure?

A Step 2

B Step 4

C Step 3

D Step 5

💡 Hint

Look for the step describing subplots creation in the right subfigure in execution_table

If we skip creating subfigures and add subplots directly to the figure, how would the execution_table change?

A Step 5 would be missing

B No change, subfigures are optional

C Step 2 would be missing, subplots created directly on figure

D Figure creation would fail

💡 Hint

Refer to execution_table step 2 about subfigure creation

Concept Snapshot

Nested subplots with subfigures:
- Create main figure with plt.figure()
- Add subfigures using fig.subfigures(rows, cols)
- Add subplots inside each subfigure with subfig.subplots(rows, cols)
- Plot data on each subplot Axes
- Show figure with plt.show()
Allows grouping plots visually inside one figure.

Full Transcript

This lesson shows how to create nested subplots using subfigures in matplotlib. First, a main figure is created. Then, subfigures are added inside the figure to divide it into sections. Each subfigure can have its own grid of subplots. We create subplots inside each subfigure and plot data on them. Finally, the figure is displayed showing all nested plots. Variables like fig, subfigs, ax1, and ax2 track the figure, subfigures, and subplot axes. Key moments include understanding why subfigures come before subplots and how each subfigure can have different layouts. The visual quiz tests understanding of variable states and execution steps. This method helps organize complex figures with grouped plots.