introduction to m atlab basic graphics

Introduction to MATLAB

Basic Graphics

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Copyright 1984 - 1998 by The MathWorks, Inc.

Basic Graphics - 2Introduction to MATLAB

Section Outline

• 2-D plotting

• Graph Annotation

• Subplots & Alternative Axes

• 3-D plotting

• Specialized plotting routines

• Patches & Images

• Saving & Exporting Figures

• Introduction to Handle Graphics

Ref: Color, Linestyle, Marker options Special characters using LaTeX



2-D Plotting

• Specify x-data and/or y-data

• Specify color, line style and marker symbol(Default values used if ‘clmnot specified)

• Syntax:

• Plotting single line:

• Plotting multiple lines:plot(x1, y1, 'clm1', x2, y2, 'clm2', ...)

plot(xdata, ydata, 'color_linestyle_marker')

Ref: Color, Linestyle, Marker options



2-D Plotting - exampleCreate a Blue Sine Wave

» x = 0:.1:2*pi;

» y = sin(x);

» plot(x,y)

» x = 0:.1:2*pi;

» y = sin(x);

» plot(x,y)

»plot_2d



Adding a Grid

• GRID ON creates a grid on the current figure

• GRID OFF turns off the grid from the current figure

• GRID toggles the grid state

»grid on



Adding additional plots to a figure

• HOLD ON holds the current plot

• HOLD OFF releases hold on current plot

• HOLD toggles the hold state

»addgraph

» x = 0:.1:2*pi;

» y = sin(x);

» plot(x,y,'b')

» grid on

» hold on

» plot(x,exp(-x),'r:*')

» x = 0:.1:2*pi;

» y = sin(x);

» plot(x,y,'b')

» grid on

» hold on

» plot(x,exp(-x),'r:*')



Controlling viewing area

• ZOOM ON allows user to select viewing area

• ZOOM OFF prevents zooming operations

• ZOOM toggles the zoom state

• AXIS sets axis range

[xmin xmax ymin ymax]

» axis([0 2*pi 0 1])» axis([0 2*pi 0 1])



Graph Annotation

TITLE

TEXTor

GTEXT

XLABEL

YLABEL

»annotation

LEGEND



Plot Editor

»plotedit

Right click (Ctrl-LFT): on graphics objects to modify properties

• Enable Plotting Editing

• Add Text

• Add Arrow

• Add Line

• Zoom In

• Zoom Out

• Rotate 3D

• [Edit] -> Copy Figure / Options



Using LaTeX in Graph Annotations

Font Type (applies inside {} or until changed):

• \fontname{ } AND \fontsize{ }

Appearance (applies inside {} or until removed):

• \bf boldface

• \it OR \sl italics OR slanted

• \rm remove text formatting (normal)

Subscript “_” or superscript “^”:

Applies to next character or {text in curly braces}

Greek letters and Symbols (prefix with “\”):

Selected symbols, e.g. '\pi' = »latex_exampRef: Special characters using LaTeX



Exercise: 2-D Plotting

Create the following graph:

fontsize (14)

sin(10t)

cos(10t)

Courier New + Bold



Solution: 2-D Plotting

» t = 0:0.01:0.5;» plot(t,sin(10*pi*t),'g-*', ... t,cos(10*pi*t),'k:o')» title(['\fontsize{14}In-Phase ({\itsolid})', ... 'and Quadrature ({\itdotted}) Signals'])» xlabel('\fontname{Courier New}\bfTime (\mus)')» ylabel('{\it''Normalized''} Signals');» text(0.2, cos(2*pi)+0.1, '\leftarrow----\rightarrow');» text(0.175, cos(2*pi)+0.2, '^\pi/_2 phase lag'); » axis([0 0.5 -1.5 1.5]);

% NOTE: Could have also used GTEXT or PLOTEDIT:% =============================================% gtext('\leftarrow----\rightarrow');% gtext('^\pi/_2 phase lag');

» t = 0:0.01:0.5;» plot(t,sin(10*pi*t),'g-*', ... t,cos(10*pi*t),'k:o')» title(['\fontsize{14}In-Phase ({\itsolid})', ... 'and Quadrature ({\itdotted}) Signals'])» xlabel('\fontname{Courier New}\bfTime (\mus)')» ylabel('{\it''Normalized''} Signals');» text(0.2, cos(2*pi)+0.1, '\leftarrow----\rightarrow');» text(0.175, cos(2*pi)+0.2, '^\pi/_2 phase lag'); » axis([0 0.5 -1.5 1.5]);

% NOTE: Could have also used GTEXT or PLOTEDIT:% =============================================% gtext('\leftarrow----\rightarrow');% gtext('^\pi/_2 phase lag');

»plot2d_soln



SubplotsSUBPLOT- display multiple axes in the same figure window

»subplot(2,2,1);

»plot(1:10)

»subplot(2,2,2)

»x = 0:.1:2*pi;

»plot(x,sin(x))

»subplot(2,2,3)

»x = 0:.1:2*pi;

»plot(x,exp(-x),’r’)

»subplot(2,2,4)

»plot(peaks)

»subplot(2,2,1);

»plot(1:10)

»subplot(2,2,2)

»x = 0:.1:2*pi;

»plot(x,sin(x))

»subplot(2,2,3)

»x = 0:.1:2*pi;

»plot(x,exp(-x),’r’)

»subplot(2,2,4)

»plot(peaks)»subplotex

subplot(#rows, #cols, index)



Alternative Scales for Axes

SEMILOGYlog Ylinear X

PLOTYY2 sets oflinear axes

LOGLOGBoth axes logarithmic

SEMILOGXlog Xlinear Y

»other_axes



3-D Line Plotting

Ref: Color, Linestyle, Marker options

» z = 0:0.1:40;

» x = cos(z);

» y = sin(z);

» plot3(x,y,z)

» z = 0:0.1:40;

» x = cos(z);

» y = sin(z);

» plot3(x,y,z)

plot3(xdata, ydata, zdata, 'clm', ...)

»plot_3d



3-D Surface Plotting

»surf_3d



Exercise: 3-D Plotting

• Data from a water jet experiment suggests the following non-linear model for the 2-D stress in the cantilever beam’s horizontal plane.

where: = localized planar stress [MPa]

x = distance from end of beam [10-1m]

y = distance from centerline of beam [10-1m]

• For the particular setup used:(x = {0 to 6}, y = {-3 to 3}, = = = 1, = -0.2)

• Plot the resulting stress distribution

= e-x[sin(x)*cos(y)]x



Solution: 3-D Plotting

» B = -0.2;

» x = 0:0.1:2*pi;

» y = -pi/2:0.1:pi/2;

» [x,y] = meshgrid(x,y);

» z = exp(B*x).*sin(x).*cos(y);

» surf(x,y,z)

» B = -0.2;

» x = 0:0.1:2*pi;

» y = -pi/2:0.1:pi/2;

» [x,y] = meshgrid(x,y);

» z = exp(B*x).*sin(x).*cos(y);

» surf(x,y,z)

»plot3d_soln



Specialized Plotting Routines

»spec_plots



Specialized Plotting Routines (2)

»spec_plots2



» a = magic(4)

a =

16 2 3 13

5 11 10 8

9 7 6 12

4 14 15 1

» image(a);

» map = hsv(16)

map =

1.0000 0 0

1.0000 0.3750 0

1.0000 0.7500 0 .....

» colormap(map)

» a = magic(4)

a =

16 2 3 13

5 11 10 8

9 7 6 12

4 14 15 1

» image(a);

» map = hsv(16)

map =

1.0000 0 0

1.0000 0.3750 0

1.0000 0.7500 0 .....

» colormap(map)

Images Reduced Memory Requirements:Images represented as UINT8 - 1 byte

»imagex

Use Row 2 of colormap for pixel (1,2)

Row 2



Example: Images

» load cape

» image(X)

» colormap(map)

» load cape

» image(X)

» colormap(map)



Saving Figures

2 files created:• .m - text file• .mat - binary data

file.

»plot3d_soln



• using the Dialog Box:File Menu / Print... >>printdlg

• from Command Line:

(Switches are optional)

• Controlling Page Layout:File Menu / Page Position>>pagedlg

Printing Figures

print -devicetype -options



• Printing image to a file:

• Print Dialog Box: (File / Print...) >>printdlg

• Command Line:

(Switches are optional)

• Copying to Clipboard:

• Options: (File / Preferences)

• Copying: (Edit / Copy Figure)

Exporting Figures

print -devicetype -options filename



Introduction to Handle Graphics

• Graphics in MATLAB consist of objects

• Every graphics objects has a unique handle and a set of properties which define it’s appearance.

• Objects are arranged in terms of a set hierarchy

Uicontrol

Image Line Patch Surface Text Light

Axes Uimenu

Figure

Root (Screen)



Hierarchy of Graphics Objects Rootobject

Figureobject

UIControlobjects

UIMenuobjects

Axes object

Figureobject

Surfaceobject

Lineobjects

Textobjects

UIControlobjects

UIMenuobjects

Axes object

Figureobject



1. Upon Creation

2. Utility Functions

0 - root object handle

gcf - current figure handle

gca - current axis handle

gco - current object handle

3. FINDOBJ

Obtaining an Object’s Handle

h_obj = findobj(h_parent, 'Property', 'Value', ...)

h_line = plot(x_data, y_data, ...)

What is the current object? • Last object created

• OR• Last object clicked

Default = 0 (root object)



Deleting Objects - DELETE

» h = findobj('Color', [0 0 1])

» delete(h)

» h = findobj('Color', [0 0 1])

» delete(h)

delete(h_object)

» addgraph



Modifying Object PropertiesUsing GET & SET

• Obtaining a list of current properties:

• Obtaining a list of settable properties:

• Modifying an object’s properties:

get(h_object)

set(h_object)

set(h_object, 'PropertyName', 'New_Value', ...)

Ref: HELPDESK - Handle Graphics Objects:\help\techdoc\infotool\hgprop\doc_frame.html



Modifying Object PropertiesUsing the Property Editor

Property List:List of properties & current values for selected object

»propedit

Object Browser:Hierarchical list of graphics objects

Property / Value Fields:Selected property & current value (modify here)



Modifying Object PropertiesUsing the RIGHT CLICK



Working with Defaults - setting

• Most properties have pre-defined 'factory' values (Used whenever property values are not specified.)

• You can define your own 'default' values to be used for creating new objects.(Put default settings in “startup.m” to apply to whole session)

Syntax:set(ancestor,'Default<Object><Property>',<Property_Val>)

Use root object (0) to apply to all new objects



» set(0, 'DefaultSurfaceEdgeColor', 'b')

» h=surf(peaks(15));

» set(0, 'DefaultSurfaceEdgeColor', 'b')

» h=surf(peaks(15));

Set the Default Surface EdgeColor to Blue & create new surface.

» set(h, 'EdgeColor', 'g')» set(h, 'EdgeColor', 'g')

Set the EdgeColor to GreenGreen

» set(h, 'EdgeColor', 'default')» set(h, 'EdgeColor', 'default')

specifies Default value

Reset back to Default Value

» set(h, 'EdgeColor', 'factory')» set(h, 'EdgeColor', 'factory')

specifies Factory value

Reset back to Factory Value

Example: Working with Defaults

»defaults



Return Default Property Value to Factory Setting:

Create a new surface:

Working with Defaults - removing

» set(gcf, 'DefaultSurfaceEdgeColor', 'factory') » set(gcf, 'DefaultSurfaceEdgeColor', 'factory')

» set(gcf, 'DefaultSurfaceEdgeColor', 'remove') » set(gcf, 'DefaultSurfaceEdgeColor', 'remove')

» h = surf(peaks(15)); » h = surf(peaks(15));

»defaults

OR

introduction to m atlab basic graphics

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