How can I plot a bode diagram with random color?

What should I add to this code to have a random color?

sys=tf(1,[1 1])
bode(sys)

[Paulo Silva]

Please always provide detailed questions so we can help you better and faster

Answer 1

[Paulo Silva]

Another strange question from sadel, I never seen someone doing so many strange things but it's all good, here's a variation from Chirag Gupta code:

sys=tf(1,[1 1]);
ColList='ymcrgbk'; %no w letter because you won't see the white line 
col=randi([1 7]);
bode(sys,ColList(col))

[sadel]

:) in another part of my code, I use the plot function this way:

plot(t,y,'DisplayName',string,'Color',[rand;rand;rand])

and this produces random colors. I'm looking for something similar with this for bode. Is it possible?

[Paulo Silva]

AllLines=findall(gcf,'type','line')

set(AllLines,'color',[rand,rand,rand])

[sadel]

Nope, let's say that I have a button and when I click it, this produces a bode diagram. I use the "hold" function to hold multiple diagrams on the same axes. I want every new diagram having a random color. I think that your code will change the color of all the lines everytime that I will click the button. I don't want that. I'm think to have dynamicLegend. Is this possible?

[Paulo Silva]

It's funny how you only give enough details after we spent time guessing what you really want!

Forget the random color and do thing the best and simplest way possible, just use hold all like this

clf

sys=tf(1,[1 1])

sys1=tf(1,[1 1 1])

hold all

bode(sys)

bode(sys1)

[Walter Roberson]

sadel, to answer your question, bode() and bodeplot() do NOT accept numeric colors. bode() also has the property that it does not return the handle to the plots it has created. Thus my answer below that uses bodeplot() which does return the handles.

[sadel]

I'm sorry Paulo but this my first program with Matlab and I don't know all the functions and their abilities yet. And my english is very bad. It's not easy to say what I want.

@Walter I think that the "hold all" function is the best that I can use.

[Paulo Silva]

just a simple example code

function testbode

figure

pbh = uicontrol(gcf,'Style','pushbutton','String','Add another',...

'Position',[10 20 60 40],...

'callback',@newbode);

axes

hold all

function newbode(obj,event)

num=ones(1,randi([1,2]));

den=ones(1,randi([3,6]));

sys=tf(num,den)

hold all

bode(sys)

end

end

[Paulo Silva]

no problem sadel, you do your best and appreciate all the help people give by voting and accepting answers, that's very important because others might have the same questions and will surely read these questions and answers.

[sadel]

Can I use Dynamic Legend with "hold all"?

[Paulo Silva]

function testbode

figure

pbh = uicontrol(gcf,'Style','pushbutton','String','Add another',...

'Position',[10 20 60 40],...

'callback',@newbode);

axes

hold all

function newbode(obj,event)

num=ones(1,randi([1,2]));

den=ones(1,randi([3,6]));

sys=tf(num,den)

hold all

sysn=evalc('sys')

[a b] = strread(sysn, '%s %s', 'delimiter',char(10))

num=char(a(2));

den=char(a(3));

linesep=char(b(2));

set(sys,'Name',[num char(10) linesep char(10) den])

bode(sys)

legend('-DynamicLegend');

end

end

Answer 2

[Chirag Gupta]

   colors =['r','b','g','y','m','k'];
   c = ceil(6*(rand))
   bode(sys,colors(c))

This will pseudo randomly choose one of the 6 colors. You can obviously add more colors to the list!

[Chirag Gupta]

MATLAB figures default to a particular color. Unless you change that setting or change the colors via code, you will get the same color.

Answer 3

[Walter Roberson]

Provided that your systems are not MIMO,

sys=tf(1,[1 1]);

h = bodeplot(sys);   %notice this is _not_ bode()
for L = findobj(h,'type','line')
  set(L,'Color', rand(1,3));
end

Note: this does not attempt to match colors between the frequency and phase components. You did ask for random color...

I do not have the appropriate toolbox to probe to determine what would be needed to use the same color between the two halves when multiple systems are being drawn on the same plot, or when bode() is used to draw an array of bode plots for a MIMO system.

[Walter Roberson]

sys=tf(1,[1 1]);

h = bodeplot(sys); %notice this is _not_ bode()

set(findobj(h,'type','line'),'Color', rand(1,3));

Not valid for MIMO systems or for specifying multiple systems to be plotted simultaneously.

[Paulo Silva]

Walter your code allows similar colors on the same axes, would be better to use hold all or make a random list of colors so each new bode plot would use just one color from the list (until the last color and it returns to the first of the list)

[Walter Roberson]

If you cannot have similar or duplicate colors, then the colors have not been chosen at random as requires by the original question ;-)

[Paulo Silva]

Good point Walter :)

Answer 4

[Niels]

Here is a solution for giving bode plots a different color than and then 'ymcrgbk' and subsequently saving the figure without unwanted changes to the legend.

sys1=tf(1,[1 1]); sys2=tf(1,[1 1 1]);

figure; hold on;

bode(sys1,'b'); bode(sys2,'r');

h1 = findobj(gcf,'Color','b','-and','linestyle','-'); set(h1,'linewidth',1,'color',[.9 .9 .9]);

h2 = findobj(gcf,'Color','r','-and','linestyle','-'); set(h2,'linewidth',2,'color',[.5 .5 .5]);

legend([h1(1) h2(1)],'system 1','system 2')

It is important to assign the first term of the handle (e.g. h1(1)) in order to avoid issues with matrix dimentions (horzcat)

Answer 5

[Chirag Gupta]

bode(sys,'r')

You can always write some code to pick a random color from a set of colors that you would like

[sadel]

No, this is not what I want. I want the program to choose a color. Not me. This code produces bode with red color.