Line styles, markers, and colors in MATLAB

Introduction

We use line styles, markers, and colors to make plots easier to understand and more visually appealing.

When you want to show different data series clearly in one plot.

When you want to highlight specific data points on a graph.

When you want to make your graph colorful and easy to read.

When you want to distinguish lines by style instead of color (for printing).

When you want to customize the look of your plot to match a report or presentation style.

Syntax

MATLAB

plot(x, y, 'LineStyle', lineStyle, 'Marker', marker, 'Color', color)

LineStyle can be '-', '--', ':', '-.'

Marker can be 'o', '+', '*', '.', 'x', 's', 'd', '^', 'v', '>', '<', 'p', 'h'

Examples

This plots a red dashed line with circle markers.

MATLAB

plot(x, y, 'LineStyle', '--', 'Marker', 'o', 'Color', 'r')

This plots a dash-dot line with square markers in the default color.

MATLAB

plot(x, y, '-.s')

This plots a green line with star markers using RGB color values.

MATLAB

plot(x, y, 'Color', [0 0.5 0], 'Marker', '*')

Sample Program

This code plots two data series with different line styles, markers, and colors to show how to customize plots in MATLAB.

MATLAB

x = 1:5;
y1 = [2 4 6 8 10];
y2 = [1 3 5 7 9];

plot(x, y1, 'LineStyle', '--', 'Marker', 'o', 'Color', 'b')
hold on
plot(x, y2, '-.', 'Marker', 's', 'Color', [1 0 0])
hold off
xlabel('X axis')
ylabel('Y axis')
title('Line styles, markers, and colors example')
legend({'Series 1', 'Series 2'})

Important Notes

You can combine short style strings like '-.s' instead of using name-value pairs.

Use hold on to plot multiple lines on the same figure.

Colors can be specified by short names ('r', 'g', 'b') or RGB triplets like [1 0 0].

Summary

Line styles change how the line looks (solid, dashed, dotted).

Markers show points on the line (circles, squares, stars).

Colors make lines easy to tell apart and more attractive.

Practice

1. Which of the following is the correct way to plot a red dashed line with circle markers in MATLAB?

easy

A. plot(x, y, 'ro-')

B. plot(x, y, '-ro')

C. plot(x, y, 'o-r')

D. plot(x, y, 'r--o')

Solution

1. Step 1: Understand MATLAB line style syntax

   In MATLAB, the format 'color lineStyle marker' is used inside the plot command, for example 'r--o' means red color, dashed line, and circle markers.

2. Step 2: Match the correct order

   The correct order is color first ('r'), then line style ('--'), then marker ('o'). So 'r--o' is correct.

3. Final Answer:

   plot(x, y, 'r--o') -> Option D

4. Quick Check:

   Color + line style + marker = 'r--o' [OK]

Hint: Remember order: color, line style, then marker [OK]

Common Mistakes:

• Putting marker before line style
• Using wrong order of characters
• Confusing color codes with markers

2. Which of the following MATLAB plot commands will produce a blue solid line with square markers?

easy

A. plot(x, y, 'b-s')

B. plot(x, y, 'sb:')

C. plot(x, y, 'b:sq')

D. plot(x, y, 'bs:')

Solution

1. Step 1: Identify the correct syntax for blue solid line with square markers

   In MATLAB, 'b' means blue, '-' means solid line, and 's' means square marker. The order is color, line style, marker.

2. Step 2: Check each option

   plot(x, y, 'b-s') 'b-s' correctly follows the order: blue color, solid line, square marker.

3. Final Answer:

   plot(x, y, 'b-s') -> Option A

4. Quick Check:

   Color + line style + marker = 'b-s' [OK]

Hint: Use 'color-lineStyle-marker' order in plot string [OK]

Common Mistakes:

• Mixing order of marker and line style
• Using invalid marker codes
• Adding extra characters like 'sq'

3. What will be the color and style of the line plotted by this command?

plot(x, y, 'g:*')

medium

A. Green dotted line with star markers

B. Green solid line with star markers

C. Green dash-dot line with star markers

D. Green dashed line with star markers

Solution

1. Step 1: Decode the plot style string 'g:*'

   'g' means green color, ':' means dotted line style, and '*' means star markers.

2. Step 2: Combine the meanings

   The line will be green, dotted, with star markers.

3. Final Answer:

   Green dotted line with star markers -> Option A

4. Quick Check:

   Color = green, line style = dotted, marker = star [OK]

Hint: ':' means dotted line, '*' means star marker [OK]

Common Mistakes:

• Confusing ':' with dash-dot line
• Mixing marker and line style symbols
• Assuming solid line by default

4. Identify the error in this MATLAB plot command:

plot(x, y, 'r--x-o')

medium

A. Color code 'r' is incorrect

B. Multiple markers specified, which is invalid

C. Line style '--' cannot be combined with markers

D. Missing semicolon at the end

Solution

1. Step 1: Analyze the plot style string 'r--x-o'

   This string tries to specify two markers: 'x' and 'o', which is not allowed in MATLAB plot format.

2. Step 2: Understand MATLAB plot style rules

   Only one marker can be specified along with one line style and one color. Multiple markers are invalid.

3. Final Answer:

   Multiple markers specified, which is invalid -> Option B

4. Quick Check:

   Only one marker allowed in plot style [OK]

Hint: Use only one marker symbol in plot style string [OK]

Common Mistakes:

• Adding multiple markers in one style string
• Ignoring MATLAB plot style syntax rules
• Thinking semicolon affects plot style

5. You want to plot two lines on the same graph: one with a green dash-dot line and circle markers, and the other with a magenta dotted line and square markers. Which MATLAB code correctly does this?

hard

A. plot(x1, y1, 'g-.o'); plot(x2, y2, 'm:s');

B. plot(x1, y1, 'g-o.'); hold on; plot(x2, y2, 'm.s:'); hold off;

C. plot(x1, y1, 'g-.o'); hold on; plot(x2, y2, 'm:s'); hold off;

D. plot(x1, y1, 'g:o-'); hold on; plot(x2, y2, 'm-s.'); hold off;

Solution

1. Step 1: Understand the required styles

   First line: green ('g'), dash-dot ('-.'), circle marker ('o'). Second line: magenta ('m'), dotted (':'), square marker ('s').

2. Step 2: Check each option for correct syntax and use of 'hold on'

   plot(x1, y1, 'g-.o'); hold on; plot(x2, y2, 'm:s'); hold off; uses 'g-.o' and 'm:s' correctly and uses 'hold on' to plot both lines on the same graph.

3. Step 3: Verify other options

   plot(x1, y1, 'g-o.'); hold on; plot(x2, y2, 'm.s:'); hold off; and D have incorrect order or invalid style strings. plot(x1, y1, 'g-.o'); plot(x2, y2, 'm:s'); misses 'hold on' so second plot overwrites first.

4. Final Answer:

   plot(x1, y1, 'g-.o'); hold on; plot(x2, y2, 'm:s'); hold off; -> Option C

5. Quick Check:

   Use correct style strings and 'hold on' to combine plots [OK]

Hint: Use 'hold on' to plot multiple lines with different styles [OK]

Common Mistakes:

• Forgetting 'hold on' to keep previous plots
• Mixing order of line style and marker
• Using invalid style strings like 'g:o-'