Designing Effective Graphics Using MATLAB

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Designing Effective Graphics Using MATLAB
The Cain Project in Engineering and Professional
Communication ENGINEERING SERIES

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The Purpose of Using Graphics

• In your own problem solving
• As part of design
• As analysis of operating data
• For persuasion and interpretation
• Dramatize relationships
• Promote identification
• Make complex information accessible

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Criteria for Good Graphics

• Purpose clear?
• Pattern and arrangement lead eye without
  distraction?
• Similar items grouped and indicated?
• Graphic hierarchy consistent?
• Fonts legible?

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Criteria for Good Graphics (contd.)

• Critical components defined?
• Essential calculations behind claims shown?
• Any significant reference or standard omitted?
• Presenters expertise demonstrated?

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Types of Graphics in Matlab

• Line graph
• 2D
• 3D

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Types of Graphics in Matlab

• Column or
• bar graph

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Types of Graphics in Matlab

• Pie graph
• Shows whole to part relationships

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Types of Graphics in Matlab
Ribbon graph
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Select Right Type of Graphic

• What Is Your Purpose?
• Problem solving?
• Persuasion and interpretation?
• Who Is the Audience?
• What are their backgrounds?
• What do they want to know?
• What Is the Context?
• Presentation?
• Report/Paper?

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Context Affects Graph Qualities

• Presentation
• Big titles, labels, etc.
• Can use any color
• Can use animation
• Report
• Smaller titles, labels, etc.
• Often just black and white
• Animation impossible

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2D Plot Tips

• Use the best line style/size for the situation.
• Think about the best placement of legend/key.
• Incorporate error bars, if necessary.
• Use gridlines sparingly.

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An Example

• You have
• Vector 1 x(00.210)
• Vector 2 sin(x)
• Vector 3 cos(x)
• You are asked to
• Plot sin(x) vs. x and cos(x) vs. x in the same
  figure.
• Customize the figure so that it is suitable for
  presentation.

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A Simple Matlab Program

• clear all
• X00.210
• sinxsin(x)
• cosxcos(x)
• plot(x,sinx,x,cosx)
• xlabel('x')
• ylabel('y')
• title(sin and cos Functions')

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Default Plot Given by Matlab
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We Want

• Titles and labels bigger
• Lines thicker
• Colors more contrasting
• Key data points visible
• Legend or labels close to lines

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How to Get What We Want
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Open the Property Editor
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Edit Figure Properties
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Edit Axes Properties
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Edit Line Properties
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So Far, A Better-Looking Figure
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Insert Legend
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Edit Legend Properties
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Insert Y Grid Line
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Final Version!
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Frequently Used Functions

• plot
• xlabel, ylabel
• title
• xlim, ylim
• axis
• legend
• errorbar

Type help xxx in Matlab command window for
detailed information on the usage of the function
xxx.
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Other 2D Plotting Commands

• loglog graph with logarithmic scales for both
  axes.
• semilogx graph with a logarithmic scale for
  x-axis and a linear scale for y-axis.
• semilogy graph with a logarithmic scale for
  y-axis and a linear scale for x-axis.
• plotyy graph with y-tick labels on the left
  and right side.

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A Whole Lot More

• 2D contour
• contour
• contourslice
• 3D plots
• plot3
• mesh
• surf
• Movie
• getframe
• movie

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Plotting in Excel
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Selecting Chart Type and Inputting Data
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Adding Labels and Selecting Location
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What do we need to change?
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Formatting your Chart
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Adding a Trendline
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Formatting the Data
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Editing the Line and Markers
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Formatting the Font
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Final Product!
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Other Features

• Logarithmic axis
• Select the axis you want to change
• Right click or select the Format option in your
  toolbar and select Format Axis
• Click on the Scale tab
• Check the box marked Logarithmic Scale

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Lead through Excellence in Engineering
Communication

• More resources are available for you
• under Engineering Communication at Connexions
  at http//cnx.org
• at the Cain Project site at http//www.owlnet.rice
  .edu/cainproj
• in your course Communication Folder in OWLSPACE.