Chapter 3 Two-Dimensional Plotshung/cs101/chap03.pdfChapter 3 Two-Dimensional Plots . ... dr.dcd.h...

dr.dcd.h CS 101 /SJC 5th Edition 1

Chapter 3 Two-Dimensional Plots


Logarithmic Scales

Some time data in logarithmic scale can have linear property.

semilogy – uses a log10 scale on the y axis

semilogx – uses a log10 scale on the x axis

loglog – uses a log10 scale on both axes


Logarithmic Scales2


Logarithmic Scales3


Controlling Axis

Command Descriptions

axis Returns axis limits: [xmin, xmax, ymin, ymax].

axis(x) Sets axis limits to x, a 1x4 vector.

axis equal Sets the aspect ratio to be equal on both axes.

axis image Same as axis equal except that the axis box fits tightly around the data.

axis square Makes the current axis box square.

axis normal Cancels the effect of axis equal and axis square

axis auto Returns the axis scaling to its default.

axis on/off Turns on/off axis labeling, tick marks.


Controlling Axis2


Controlling Axis3


Controlling Axis4


Controlling Axis5


Controlling Axis6


Creating Multiple Plots by hold

Multiple plots on the same axes by use hold on/off to enable and disable overwriting


Creating Multiple Plots by figure

Creating multiple figure windows by using figure(figure_id) to create a new figure.

gcf returns the figure_id


Creating Multiple Plots by subplot

Multiple plots by using subplot(m,n,p) to divide the current figure into an m-by-n grid and creates a subplot in the position specified by p.

Frame id is assigned in a row-order.


Creating Multiple Plots by subplot2

Subplot frames can have different sizes as long as they are not overlaid.


Creating Multiple Plots by subplot3

Multiple plots by using subplot(row, col, n) to place at the nth sub-axes in a row-by-col grid.


Specially Spaced Data

Operators that produce equally-spaced samples:

first:incr:last

linspace(first,last,n)

Operator that produces logarithmic spacing samples:

logspace(first,last,n)

If n is not specified then 50 equally-spaced samples are producred. i.e.

logspace(first,last)=linspace(first,last,50)


Example 3.1

Show y=x2-10x+25 over the range [0,10] in different scales.


Enhanced Lines

Properties of a plotted line can be set by plot(x,y,’PropertyName’,value, …)

4 properties associated with plotted line

LineWidth

MarkerSize

MarkerFaceColor

MarkerEdgeColor

For example:

plot(x,y,’LineWidth’,3,’MarkerSize’,3)


Enhanced Lines2


Enhanced Text Strings

Use stream modifiers to enhance text strings (titles, labels, etc.) such as bold face, italics, and special symbols.

Common stream modifiers:

\bf, \it – bold face, italics

\rm – remove modifiers

\fontname{name} – specify font name

\fontsize{size} – specify font size

_{txt} – specify txt as a subscript

^{txt} - specify txt as a superscript

\color{color} – specify text color


Enhanced Text Strings2

Character Sequence

Greek Symbol

Character Sequence

Greek Symbol

Character Sequence

Mathmetic Symbol

\alpha a \int

\beta b \cong

\gamma g \Gamma G \sim

\delta d \Delta D \infty

\epsilon e \pm

\eta h \leq

\theta q \geq

\lambda l \Lambda L \neq

\mu m \propto

\nu n \div

\pi p \Pi P \circ

\phi f \leftrightarrow

\rho r \leftarrow

\sigma s \Sigma S \rightarrow

\tau t \uparrow

\omega w \Omega W \downarrow


Enhanced Text Strings3

For example: the following expression

'\fontsize{18}\color{blue}\int_{\Omega} \color{green}\int_{\Gamma}

\color{black}(\nu^{2}+3\nu\mu) \color{red}d\nud\mu'

Produces the following text:


Place Random Text

A text string can be randomly placed by:

text(x, y, string, <modifiers>)

Position modifiers are used to specify alignment:

HorizontalAligment: Left/Center/Right

VerticalAlignment: Top/Middle/Bottom

For example:

text(2,1.4,'\omega \color{red}abc\rm',… 'HorizontalAlignment', 'Center')


Example 3.2

Plot function y(t)=10 e-t/t sin(wt) over [0,10]


Homework Assignment #6

3.7 Exercises

Page 123: 3.1, 3.6, 3.11, 3.12

This assignment is due by next week.

Late submission will be penalized.


Polar Plots

Polar is a special plotting function, which plots data in polar coordinates.

The general form of polar function

polar(x, y)

Data in frequency domain using polar plots have a better illustration than by using linear plots.


Example 3.2 Refreshed

Plot function y(t)=10 e-t/t sin(wt) over [0,10]


Example 3.2 Refreshed2

Polar plot function y(t)=10 e-t/t sin(wt) over [0,10]


Example 3.3

Plot gain of a cardioid microphone 2g cos(q)


Additional Plotting Functions

Function Descriptions

bar Creates a vertical bar plot.

barh Creates a horizontal bar plot

stairs Creates a stair plot

stem Creates a vertical bar plot

compass Creates a polar plot with an arrow drawn from the origin to the location of each point

pie Creates a pie bar plot. This function determines the percentage of each item.

If pie(p, q) syntax is used, q is called an explode array which controls whether individual pie slices are separated from the rest of the pie.


Additional Plotting Functions2

To create multiple-bar chart, data needs to be arranged in column major order.



Basically, stairs plots are the envelopes of the bar charts.



Basically, stem plots can be considered as narrowed bar charts.



The points to compass plot are in Cartesian coord., not in polar form.



If pie(p, q) syntax is used, q is called an explode array which controls whether individual slices are separated from the pie.


Homework Assignment #7

Quiz 3.1

Page 114: 7

3.7 Exercises

Page 123: 3.5, 3.14

This assignment is due by next week.

Late submission will be penalized.

Chapter 3 Two-Dimensional Plotshung/cs101/chap03.pdfChapter 3 Two-Dimensional Plots . ... dr.dcd.h...

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