Help With Graphing on the Same Plot

Hello! I am hoping someone can help me find a way to have these graphs lined up so the x-axis with months on them line up. ( 200 months in the scallops line up with 200 months in the ray population and such). I think the name for it is a stacked time series.

Here's my code! Thank you very much in advance.

% Trohpic Cascade to calculate the changes in population in scallops and
% cownose rays based on interactions with each other
clear
% Inputs
R(1) = 100; % Initial poplation of cownose rays
B(1) = 10000;   % Initial population of scallops

dR = .02;    % Death rate of rays in abscence of scallops
gamma = 0.05;   % Growth rate of scallops in absence of cownose rays

T = 1000;   % Time in months that the simulation will be run for

Rcrit = 83; % Critical value of rays to support a stable scallop population
Bcrit = 6000;   % Critical value of scallops needed to support a stable cownose ray population

for t = 1 : T-1
    B(t+1) = B(t) + computeDeltaB(gamma, R(t), Rcrit, B(t));
    R(t+1) = R(t) + computeDeltaR(dR, B(t), Bcrit, R(t));
end

figure;
plot(B); 
hold on
xlabel('time (months)', 'FontSize' ,18);
ylabel ('B (Scallops)', 'FontSize', 18);
title('Scallops Over Time', 'FontSize', 18)


figure;
plot(R);
xlabel('time (months)', 'FontSize', 18);
ylabel ('R (Rays)', 'FontSize', 18);
title(' Rays over Time', 'FontSize', 18)


hold off

Answer 1

[Star Strider]

Plotting specific time vectors as well as ‘R’ or ‘B’ might do what you want. (We cannot run your code.)

Example —

plot(tR, R)

and

plot(tB, B)

Second option — plot them both on the same axes:

figure
plot(tR, R)
hold on
plot(tB,B)
hold off
xlabel('time (months)', 'FontSize' ,18);
ylabel('Population')
legend('Rays', 'Scallops', 'Location','best')

.

[Anneliese Fensch]

When I do this, I recieve an error saying that tR and tB are unknown functions.

[Star Strider]

O.K. Creating the time vectors was just a suggestion to be certain that they plotted correctly. If your results are a differential equation integration using one of the numeric solvers such as ode45, it should have produced a time vector as well, so I would use that vector to be certain the the prey and predator variables are plotted correctly with respect to time.

To plot them together on one set oif axes (if that is what you want to do), just do this, then:

figure
plot(R)
hold on
plot(B)
hold off
xlabel('time (months)', 'FontSize' ,18);
ylabel('Population')
legend('Rays', 'Scallops', 'Location','best')

Actually, what you describe as wanting are a subplot array, so do this:

figure
subplot(2,1,1)
plot(R)
ylabel('Rays')
subplot(2,1,2)
plot(B)
ylabel('Scallops')
xlabel('time (months)', 'FontSize' ,18);

A similar option (if you have R2019a or later) is tiledlayout, and still another option if you have R2018b or later, is stackedplot, so you might want to check those as well.

.

[Anneliese Fensch]

Thank you so much! The subplot is exactly what I needed.

I'm pretty new to MATLAB, so the little details like this are mysteries to me right now.

[Star Strider]

As always, my pleasure!

Answer 2

[Asad (Mehrzad) Khoddam]

The second figure command, creates a new figure,

you can comment it out:

% The second graph
%figure;
plot(R);
xlabel('time (months)', 'FontSize', 18);
ylabel ('R (Rays)', 'FontSize', 18);
title(' Rays over Time', 'FontSize', 18)
hold off

[Anneliese Fensch]

This is not quite what I wanted. When I use this, it graphs them both on the same graph. I would like to have two separate graphs stacked together, so kind of like the example in the picture below, but with my code instead of code on wolves and moose.

I really appreciate the help! I'm quite new to MATLAB, so this might be super easy - I just have no idea what I am doing.

Answer 3

[Asad (Mehrzad) Khoddam]

% Trohpic Cascade to calculate the changes in population in scallops and
% cownose rays based on interactions with each other
clear
% Inputs
R(1) = 100; % Initial poplation of cownose rays
B(1) = 10000;   % Initial population of scallops

dR = .02;    % Death rate of rays in abscence of scallops
gamma = 0.05;   % Growth rate of scallops in absence of cownose rays

T = 1000;   % Time in months that the simulation will be run for

Rcrit = 83; % Critical value of rays to support a stable scallop population
Bcrit = 6000;   % Critical value of scallops needed to support a stable cownose ray population

for t = 1 : T-1
    B(t+1) = B(t) + computeDeltaB(gamma, R(t), Rcrit, B(t));
    R(t+1) = R(t) + computeDeltaR(dR, B(t), Bcrit, R(t));
end

yyaxis left;
plot(t,B); 

ylabel ('B (Scallops)', 'FontSize', 18);
title('Scallops Over Time', 'FontSize', 18);

yyaxis right
plot(t,R);
xlabel('time (months)', 'FontSize', 18);
ylabel ('R (Rays)', 'FontSize', 18);
title(' Rays over Time', 'FontSize', 18)

xlabel('time (months)', 'FontSize' ,18);


hold off

[Anneliese Fensch]

This didn't quite work either.... I recieved the graph below. Again, I would like it if it were two separate graphs but stacked on top of each other so the x axises are lined up.

[Asad (Mehrzad) Khoddam]

If you want to have two different plots, use subplot:

% Trohpic Cascade to calculate the changes in population in scallops and
% cownose rays based on interactions with each other
clear
% Inputs
R(1) = 100; % Initial poplation of cownose rays
B(1) = 10000;   % Initial population of scallops

dR = .02;    % Death rate of rays in abscence of scallops
gamma = 0.05;   % Growth rate of scallops in absence of cownose rays

T = 1000;   % Time in months that the simulation will be run for

Rcrit = 83; % Critical value of rays to support a stable scallop population
Bcrit = 6000;   % Critical value of scallops needed to support a stable cownose ray population

for t = 1 : T-1
    B(t+1) = B(t) + computeDeltaB(gamma, R(t), Rcrit, B(t));
    R(t+1) = R(t) + computeDeltaR(dR, B(t), Bcrit, R(t));
end

subplot(2,1,1)
plot(t,B); 
xlabel('time (months)', 'FontSize', 18);
ylabel ('B (Scallops)', 'FontSize', 18);
title('Scallops Over Time', 'FontSize', 18);

subplot(2,1,2)
plot(t,R);
xlabel('time (months)', 'FontSize', 18);
ylabel ('R (Rays)', 'FontSize', 18);
title(' Rays over Time', 'FontSize', 18)

xlabel('time (months)', 'FontSize' ,18);


hold off