Matlab Programming - Plottingrvoyles/Classes/MET164/... · 2017-04-11 · Matlab has a default sequence of colors for the plots that are used, unless you define the colors b blue

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Matlab Programming - Plotting

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Today we are going to learn details about plotting

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The “close all” command at the beginning of a script will

close all of the previous figures

figure (number): will open a specific figure that you can use to

plot data

plot: will plot the data in the current figure (or open a figure if

there are none open)

>> t = [0:0.1:5];

>> y = sin(t);

>> figure(1)

>> figure(2)

>> plot(t,y)

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Matlab has a default sequence of colors for the plots that

are used, unless you define the colors

b blue plot(x,y,’b’)

g green plot(x,y,’g’)

r red plot(x,y,’r’)

c cyan plot(x,y,’c’)

m magenta plot(x,y,’m’)

y yellow plot(x,y,’y’)

k black plot(x,y,’k’)

w white plot(x,y,’w’)

Without the letters, the plot function will always start with the color at the

top of this list and work down

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Matlab always uses solid lines, unless indicated to use a

different type of line

- solid plot(x,y,’-’)

: dotted plot(x,y,’:’)

-. dashdot plot(x,y,’-.’)

-- dashed plot(x,y,’--’)

These can be used in combination with the colors as well

plot(x,y,’--g’) or plot(x,y,’g--’) produces a figure with a green

dashed line

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The specific data points used for the plot can be

highlighted with specific characters

. point o circle

x x-mark + plus

* star s square

d diamond v triangle (down)

^ triangle (up) < triangle (left)

> triangle (right) p pentagram

h hexagram

These can be used in combination with the colors/symbols

plot(x,y,’x--g’) or plot(x,y,’gx--’) produces a figure with a green

dashed line with an “x” at all of the data points

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We can code labels, titles, etc. for the figure within the

script or using the drop down menus from the figure

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We can code labels, titles, etc. for the figure within the

script

xlabel(‘length (cm)’)

ylabel(‘frequency (Hz)’)

title(‘Data Model Comparison’)

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The font and font size of the text can be adjusted for the

figures as well

A handle contains all of the information that will be used for the

text

set(gca,'Fontname','timesNewRoman','Fontsize',12)

set(gca,'Fontname','timesNewRoman','Fontsize',20)

gca is a function to “get current axis” that returns a handle to the axis

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The font and font size of the text can be adjusted for

each part as well

xlabel('length (cm)','fontsize',14)

ylabel('frequency (Hz)','fontsize',18)

title('Data Model Comparison','fontname','Algerian','fontsize',20)

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Legends are included in plots to help define the different

types of data

legend('theoretical','experimental')

set font name and size using the

handle

location can be used to place the

legend in a specific location in the

text

there are 18 specific locations where

the legend can be placed including

best

compass locations

legend('theoretical','experimental‘,’location’,’southwest’)

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Text can be placed at any location on the plots as well

that is not part of the legend

text(15,100,'under the plot','fontsize',16)

the figure handle will not adjust the font name or size

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We can also define the size of each axis of the plot

axis: command that allows you to

adjust your axis

tight

equal

square

off

axis([xl xu yl yu])

axis([0 60 75 300])

axis([xl xu yl yu zl zu]): for 3D

plots

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The tick marks of each axis can be controlled as well

and grid lines can be included

include the tick marks in the handle

‘xtick’

‘ytick’

turn on the grid grid on

set(gca,'Fontname','timesNewRoman','Fontsize',14,'xtick',[10:5:60])

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Multiple graphs may be put on the same figure in two

different ways

At the same time

plot(length,theory,length,experimental)

follows the color sequence

Or at different times

plot(length,theory)

hold on

plot(length,experimental)

the color needs to be defined or each subsequent plot will start with ‘blue’

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The line width for the different plots can be changed as

well

But, each plot needs to be plotted separately with the ‘hold on’ command

plot(length.*100,theory_3,'--','LineWidth',6)

hold on;

plot(length.*100,experimental_3,'r','LineWidth',2)

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We can also place multiple different plots in the same

figure

subplot(2,1,1)

plot(length,theory)

hold on

plot(length,experimental)

subplot(2,1,2)

plot(length2,theory2)

hold on

plot(length2,experimental2)

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We can also graph different axis types

plotyy: places two different y-axes

semilogx: x-axis is log scale

semilogy: y-axis is log scale

loglog: both x and y axes are log scale

hist: histogram chart

pie: pie chart

polar: polar graph

bar: bar chart

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We can also graph 3D plots and surface plots as well

>> plot3(t,y,y1)

>> grid on

include the third axis as

well

zlabel

axis command

01

23

45

-1

-0.5

0

0.5

1-1

-0.5

0

0.5

1

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In conclusion

There are numerous types and ways to plot with Matlab

The help files and google are friends to determine the ways to

plot what you need