Plt.subplots with rows and columns in Matplotlib - Step-by-Step Execution

Concept Flow - Plt.subplots with rows and columns

Call plt.subplots(rows, cols)

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Create Figure object

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Create Axes array with shape (rows, cols)

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Return Figure and Axes

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User plots on each Axes

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Display or save the figure

The function plt.subplots creates a figure and a grid of subplots (axes) arranged in rows and columns, returning them for plotting.

Execution Sample

Matplotlib

import matplotlib.pyplot as plt
fig, axs = plt.subplots(2, 3)
axs[0, 0].plot([1, 2], [3, 4])
plt.show()

This code creates a 2-row by 3-column grid of plots and draws a line on the first subplot.

Execution Table

Step	Action	Result	Notes
1	Call plt.subplots(2, 3)	Figure and 2x3 Axes array created	Figure is empty, axes ready for plotting
2	Access axs[0, 0]	First subplot Axes object	Top-left plot in grid
3	Plot line on axs[0, 0]	Line appears on first subplot	Data points (1,3) and (2,4) connected
4	Call plt.show()	Figure window opens with 6 subplots	Only first subplot has a line, others are empty
5	End	Execution stops	All plots displayed

💡 All subplots created and displayed, program ends after plt.show()

Variable Tracker

Variable	Start	After Step 1	After Step 3	Final
fig	None	Figure object	Figure object	Figure object
axs	None	2x3 numpy array of Axes	2x3 numpy array of Axes with line on axs[0,0]	Same as after step 3

Key Moments - 3 Insights

Why is axs a 2D array and not a list?

Because plt.subplots with rows and columns returns a numpy array shaped (rows, cols), so axs[0,0] accesses the first subplot. See execution_table step 2.

What happens if you try axs[3,0] in this example?

It causes an IndexError because axs only has 2 rows (indices 0 and 1). See variable_tracker for axs shape.

Why do only some subplots show data after plotting?

Because we only plotted on axs[0,0]. The other subplots are empty by default. See execution_table step 3 and 4.

Visual Quiz - 3 Questions

Look at the execution table, what is the shape of axs after step 1?

A 1D array with 6 Axes

B List of 2 Axes

C 2D array with shape (2, 3)

D Single Axes object

💡 Hint

Check execution_table row 1 under Result describing axs shape

At which step does the first line appear on the plot?

A Step 3

B Step 2

C Step 1

D Step 4

💡 Hint

See execution_table step 3 where plotting happens

If you change plt.subplots(2, 3) to plt.subplots(3, 2), how does axs shape change?

A axs becomes 1D array

B Shape becomes (3, 2)

C Shape stays (2, 3)

D axs becomes a list

💡 Hint

The rows and columns arguments define axs shape as (rows, cols)

Concept Snapshot

plt.subplots(rows, cols) creates a Figure and a grid of Axes with given rows and columns.
Returns (fig, axs) where axs is a 2D array of Axes.
Access subplots by axs[row, col].
Plot on each Axes independently.
Call plt.show() to display all subplots.

Full Transcript

This visual execution trace shows how plt.subplots with rows and columns works. First, plt.subplots(2, 3) creates a figure and a 2 by 3 grid of subplot axes. The axs variable holds these axes in a 2D array. We then plot a line on the first subplot axs[0, 0]. Calling plt.show() opens a window displaying all six subplots, with only the first showing the line. The variable tracker confirms fig and axs states after each step. Key moments clarify common confusions about axs shape and indexing. The quiz tests understanding of axs shape, plotting step, and effect of changing rows and columns. The snapshot summarizes the main points for quick reference.