Plotting within a FOR loop

Hello, some help please...

I have three column vectors T_e, T_c and P (each of size 56x1). I need to plot T_e vs P (at constant T_c). T_e is a vector in which the first 8 elements get repeated 7 times. P has the values corresponding to each T_e at the corresponding values of T_c. I have displayed the column vectors below:

T_e=[10    15    20    25    30    35    40    45    10    15    20    25    30
  35    40    45    10    15    20    25    30    35    40    45    10    15
  20    25    30    35    40    45    10    15    20    25    30    35    40
  45    10    15    20    25    30    35    40    45    10    15    20    25
  30    35    40    45]'
T_c=[ 140   140   140   140   140   140   140   140   130   130   130   130   130
  130   130   130   120   120   120   120   120   120   120   120   110   110
  110   110   110   110   110   110   100   100   100   100   100   100   100
  100    90    90    90    90    90    90    90    90    70    70    70    70
  70    70    70    70]'

P=[6400     6950        7450        7950        8350        8750
9100        9400        6250        6750        7200        7600
7950        8250        8500        8750        6100        6500
6850        7200        7450        7700        7900        8050
5850        6200        6450        6700        6900        7100
7200        7300        5550        5800        6050        6200
6350        6450        6500        6500        5200        5400
5550        5650        5700        5750        5750        5700
4400        4460        4470        4440        4380        4280
4150        3990]'

Please note that despite how it is being displayed here, all three are column vectors - I copied them from the workspace.

I need a generalized code that will be able to plot T_e vs P for this data set and many other data sets too.

The program I wrote for this is:

for i <= 1:size(T_e)
  if T_e(i) <= T_e(i+1)
      i = i+1;
  else
      disp(i)
      plot(T_e(1:i),Powerinput(1:i))
      i = i+1;
  end
end

It seems to work reasonably well. The trouble is it generates 6 different plots - I want one. It connects the end point of the first curve to the start point of the second curve with a straight line. I want the curves to be independent lines and of different colors. How do I do that?

And although the for loop is supposed to end at size(x), it keeps going one higher and ends with this warning:

Index exceeds matrix dimensions.

Error in proplot (line 15) if EvaporatingT(i) <= EvaporatingT(i+1)

What I ideally want is this:

plot(EvaporatingT(1:8),Powerinput(1:8),'b', EvaporatingT(9:16),Powerinput(9:16),'g',  EvaporatingT(17:24),Powerinput(17:24),'m', EvaporatingT(25:32),Powerinput(25:32),'r', EvaporatingT(33:40), Powerinput(33:40),'c', EvaporatingT(41:48), Powerinput(41:48),'k', EvaporatingT(49:56), Powerinput(49:56),'y');
hold on
plot(EvaporatingT(1:8), Massflowrate(1:8),'b', EvaporatingT(9:16),Massflowrate(9:16),'g', EvaporatingT(17:24),Massflowrate(17:24),'m', EvaporatingT(25:32),Massflowrate(25:32),'r', EvaporatingT(33:40),Massflowrate(33:40),'c', EvaporatingT(41:48), Massflowrate(41:48),'k', EvaporatingT(49:56),Massflowrate(49:56),'y');
xlabel('EvaporatingT'); ylabel('Powerinput')
legend('CondensingT = 140','CondensingT = 130','CondensingT = 120','CondensingT = 110','CondensingT = 100','CondensingT = 90','CondensingT = 70','Location','Northwest')

but in a program so that I can apply it to many different data sets.

Any assistance would be greatly appreciated. Thanks very much in advance.

Answer 1

[Joseph Cheng]

a for loop to do the first part can be then used for the rest of your plots

plot(EvaporatingT(1:8),Powerinput(1:8),'b', EvaporatingT(9:16),Powerinput(9:16),'g',  EvaporatingT(17:24),Powerinput(17:24),'m', EvaporatingT(25:32),Powerinput(25:32),'r', EvaporatingT(33:40), Powerinput(33:40),'c', EvaporatingT(41:48), Powerinput(41:48),'k', EvaporatingT(49:56), Powerinput(49:56),'y');

can be simplified to something like this

for i =1:96/8
x(:,i) = [1:8]';
end
x=x(:);
y=randi(100,1,96);
cc=hsv(length(x));
figure,hold on,cc=hsv(length(x));
for i =1:8:length(x)
plot(x(i:i+7),y(i:i+7),'color',cc(i,:))
end

[Gautam]

Thanks very much for the reply. In your code you have assumed that the data repeats after every 8 elements - which is correct for this data set, but wouldn't apply to all other data sets - that is the reason I need a program to identify when the one set of data points ends and the other begins, eg.: the program I posted above returns index = 8 and plots T_e and Powerinput from T_e = 10:45 as one curve. The second set of 10:45 will need to be plotted as a second curve. Please copy the data and use the program to get a complete idea of what I mean. Thank you once again.

[Joseph Cheng]

well i can't really do that because you didn't supply powerinput and other things besides T_E T_c and P. The sample i gave with dummy numbers can be adapted to fit your needs