INF040 - MathLab-Tranpar. 2

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ATLAB

Basic Graphics

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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

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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')

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2-D Plotting - example

Create 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

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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

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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:*')**

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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])**

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Graph Annotation

TITLE

TEXT

or

GTEXT

XLABEL

YLABEL

»annotation

LEGEND

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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

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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_examp

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Exercise: 2-D Plotting

Create the following graph:

fontsize (14)

sin(10

t)

cos(10

t)

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Solution: 2-D Plotting

» t = 0:0.01:0.5;

**» plot(t,sin(10pit),'g-*', ...**

**t,cos(10pit),'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(10pit),'g-*', ...**

**t,cos(10pit),'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

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Subplots

SUBPLOT- 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

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Alternative Scales for Axes

SEMILOGY

log Y

linear X

PLOTYY

2 sets of

linear axes

LOGLOG

Both axes

logarithmic

SEMILOGX

log X

linear Y

»other_axes

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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', ...)

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3-D Surface Plotting

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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

-1

m]

y = distance from centerline of beam [10

-1

m]

• 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)]

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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(Bx).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(Bx).sin(x).*cos(y);**

»

surf(x,y,z)

»plot3d_soln

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Specialized Plotting Routines

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Specialized Plotting Routines (2)

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» 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)

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Example: Images

» load cape

» image(X)

» colormap(map)

» load cape

» image(X)

» colormap(map)

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Saving Figures

2 files created:

• .m

- text file

• .mat - binary data file.

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• using the Dialog Box:

File Menu / Print...

>>printdlg

• from Command Line:

(Switches are optional)

• Controlling Page Layout:

File Menu / Page Position

>>pagedlg

Printing Figures

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• 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

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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)

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Hierarchy of Graphics Objects

_Root

object

Figure

object

UIControl

objects

UIMenu

objects

Axes object

Figure

object

Surface

object

Line

objects

Text

objects

UIControl

objects

UIMenu

objects

Axes object

Figure

object

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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

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Deleting Objects - DELETE

» h = findobj('Color', [0 0 1])

» delete(h)

» h = findobj('Color', [0 0 1])

» delete(h)

delete(h_object)

» addgraph

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Modifying Object Properties

Using 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:

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Modifying Object Properties

Using 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 &

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Modifying Object Properties

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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>)

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» 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 the EdgeColor to Green

Green

» set(h, 'EdgeColor', 'default')

specifies Default value

Reset back to

Default Value

» set(h, 'EdgeColor', 'factory')

specifies Factory value

Reset back to Factory Value

Example: Working with Defaults

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Return Default Property Value to Factory Setting:

Create a new surface:

Working with Defaults - removing

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

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

» h = surf(peaks(15));

»defaults

OR