Axis control and formatting in MATLAB - Mini Project: Build & Apply

Axis control and formatting

📖 Scenario: You are creating a simple plot to show the relationship between two sets of data points. You want to control the axis limits and add labels to make the plot clear and easy to understand.

🎯 Goal: Build a MATLAB script that plots data points, sets specific axis limits, and adds axis labels with formatting.

📋 What You'll Learn

Create vectors for x and y data points

Set axis limits using axis

Add labels to x-axis and y-axis using xlabel and ylabel

Format axis labels with font size and font weight

💡 Why This Matters

🌍 Real World

Controlling axis limits and formatting labels is important when creating clear and professional graphs for reports, presentations, or data analysis.

💼 Career

Many jobs in engineering, science, and data analysis require creating plots that communicate data clearly. Knowing how to control axes and labels is a basic but essential skill.

1

Create data vectors

Create two vectors called x and y with these exact values: x = [1 2 3 4 5] and y = [2 4 6 8 10].

MATLAB

% Create vectors x and y with the given values
% Your code here

Hint

Use square brackets to create vectors in MATLAB, separate numbers with spaces.

2

Plot data and set axis limits

Use plot(x, y) to plot the data points. Then set the axis limits to [0 6 0 12] using the axis function.

MATLAB

plot(x, y);
% Set axis limits to [0 6 0 12]
% Your code here

Hint

Use plot(x, y) to draw the graph and axis([xmin xmax ymin ymax]) to set limits.

3

Add axis labels

Add an x-axis label with the text 'Time (seconds)' using xlabel. Add a y-axis label with the text 'Distance (meters)' using ylabel.

MATLAB

xlabel('Time (seconds)');
ylabel('Distance (meters)');
% Your code here

Hint

Use xlabel('text') and ylabel('text') to add labels.

4

Format axis labels

Set the font size of both axis labels to 14 and font weight to 'bold' using the set function with the label handles returned by xlabel and ylabel.

MATLAB

% Get handles for labels
hx = xlabel('Time (seconds)');
hy = ylabel('Distance (meters)');
% Set font size to 14 and font weight to bold
% Your code here

Hint

Store the output of xlabel and ylabel in variables, then use set to change properties.

Practice

1. What does the MATLAB command axis([0 10 0 5]) do to a plot?

easy

A. Sets the x-axis limits from 0 to 10 and y-axis limits from 0 to 5

B. Sets the axis color to RGB values [0 10 0 5]

C. Creates a grid with 10 rows and 5 columns

D. Labels the axes with numbers 0, 10, 0, and 5

Solution

1. Step 1: Understand the axis function input

   The axis function with a vector of four numbers sets axis limits: [xmin xmax ymin ymax].

2. Step 2: Apply the given limits

   Here, [0 10 0 5] means x-axis from 0 to 10 and y-axis from 0 to 5.

3. Final Answer:

   Sets the x-axis limits from 0 to 10 and y-axis limits from 0 to 5 -> Option A

4. Quick Check:

   axis([xmin xmax ymin ymax]) = set axis limits [OK]

Hint: Remember axis([xmin xmax ymin ymax]) sets axis limits [OK]

Common Mistakes:

• Confusing axis limits with colors
• Thinking axis sets labels or grid size
• Using axis without four numbers

2. Which of the following is the correct syntax to set the x-axis label to 'Time (s)' in MATLAB?

easy

A. labelx('Time (s)')

B. xlabel('Time (s)')

C. setxlabel('Time (s)')

D. xaxislabel('Time (s)')

Solution

1. Step 1: Recall MATLAB function for x-axis label

   The function to set x-axis label is xlabel with the label text as input.

2. Step 2: Check syntax correctness

   xlabel('Time (s)') correctly sets the label. Other options are invalid function names.

3. Final Answer:

   xlabel('Time (s)') -> Option B

4. Quick Check:

   Use xlabel('text') to label x-axis [OK]

Hint: Use xlabel('text') exactly to label x-axis [OK]

Common Mistakes:

• Using wrong function names like setxlabel
• Forgetting quotes around label text
• Confusing xlabel with axis or title

3. What will be the effect of the following MATLAB code?

plot(1:5, [2 4 6 8 10]);
axis([0 6 0 12]);
xticks([0 2 4 6]);
yticks([0 6 12]);

medium

A. Plot points with x-axis from 0 to 6, y-axis from 0 to 12, x-ticks at 0,2,4,6 and y-ticks at 0,6,12

B. Plot points with default axis limits and ticks

C. Error because xticks and yticks require vectors of length 5

D. Plot with reversed axes limits

Solution

1. Step 1: Analyze axis limits

   axis([0 6 0 12]) sets x-axis from 0 to 6 and y-axis from 0 to 12.

2. Step 2: Analyze tick settings

   xticks([0 2 4 6]) sets x-axis ticks at 0, 2, 4, 6; yticks([0 6 12]) sets y-axis ticks at 0, 6, 12.

3. Final Answer:

   Plot points with x-axis from 0 to 6, y-axis from 0 to 12, x-ticks at 0,2,4,6 and y-ticks at 0,6,12 -> Option A

4. Quick Check:

   axis + xticks + yticks control limits and ticks [OK]

Hint: axis sets limits; xticks/yticks set tick marks [OK]

Common Mistakes:

• Assuming default ticks remain after setting axis
• Thinking xticks/yticks need same length as data
• Confusing axis limits with tick positions

4. Identify the error in this MATLAB code snippet for setting axis limits and fix it:

plot(1:3, [5 10 15])
axis(0 3 0 20)

medium

A. Limits must be strings; use axis('0 3 0 20')

B. axis function does not set limits; use xlim and ylim instead

C. Missing square brackets around limits; should be axis([0 3 0 20])

D. No error; code runs fine

Solution

1. Step 1: Check axis function syntax

   The axis function requires a vector input for limits, enclosed in square brackets.

2. Step 2: Identify missing brackets

   The code uses axis(0 3 0 20) without brackets, causing syntax error.

3. Final Answer:

   Missing square brackets around limits; should be axis([0 3 0 20]) -> Option C

4. Quick Check:

   axis([xmin xmax ymin ymax]) needs brackets [OK]

Hint: Always use square brackets for axis limits [OK]

Common Mistakes:

• Omitting brackets around axis limits
• Using strings instead of numeric vectors
• Confusing axis with xlim or ylim functions

5. You want to create a plot with x-axis from -5 to 5, y-axis from -10 to 10, and custom ticks every 2 units on both axes. Which MATLAB code correctly achieves this?

hard

A. plot(x,y); axis([-5 5 -10 10]); xticks([-5 2 5]); yticks([-10 2 10]);

B. plot(x,y); axis([-5 5 -10 10]); xticks(-5:5); yticks(-10:10);

C. plot(x,y); xlim([-5 5]); ylim([-10 10]); ticks([-5 5], [-10 10]);

D. plot(x,y); axis([-5 5 -10 10]); xticks(-5:2:5); yticks(-10:2:10);

Solution

1. Step 1: Set axis limits correctly

   axis([-5 5 -10 10]) sets x-axis and y-axis limits as required.

2. Step 2: Set ticks every 2 units

   xticks(-5:2:5) creates ticks at -5, -3, -1, 1, 3, 5; similarly for y-axis with yticks(-10:2:10).

3. Step 3: Check other options

   plot(x,y); axis([-5 5 -10 10]); xticks([-5 2 5]); yticks([-10 2 10]); sets ticks incorrectly (missing intermediate values). plot(x,y); xlim([-5 5]); ylim([-10 10]); ticks([-5 5], [-10 10]); uses invalid ticks function. plot(x,y); axis([-5 5 -10 10]); xticks(-5:5); yticks(-10:10); sets ticks every 5 units, not 2.

4. Final Answer:

   plot(x,y); axis([-5 5 -10 10]); xticks(-5:2:5); yticks(-10:2:10); -> Option D

5. Quick Check:

   Use axis for limits and colon operator for ticks [OK]

Hint: Use colon operator for ticks: start:step:end [OK]

Common Mistakes:

• Setting ticks with wrong intervals
• Using non-existent ticks() function
• Confusing axis limits with tick values