![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1359778/image.png)
Create a 3d plot, by changing a variable while using linear programming and system optimization.
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IN MATLAB R2022b - academic use.
I need help creating a 3d plot.
I am using the function 'linprog' to find the least cost conservation plan for the Colorado River in Arizona, Nevada, and California. I have costs and conservation volums, as well as prepetual conservation (purchassing land from farmers, installing low-flow showers/toilets) and one year conservation (fallowing farm land/crop rotation).
As my time considered for conservation needs increases [line 2 variable 'yo'] the usefulness of the more expensive, propetual conservation, options become more ecconomical. My figure [line 45-51] plots the different conservation options and how much of each was sellected each year.
I want to turn this 2d plot into a 3d plot so the x and y become x and z (vertical height maintained) and the y axis shown the different amount of time considered
Then I want to do this again (seperatly) but with the change in Annual Budget [line 5] which also impacts the decision space.
I expect the function 'linprog' needs to be solved multiple times for each change in a variable. I dont know the best (or any) way to keep the data and display it in a 3d space.
Code Below:
For these varibles ['j' conservation and 'F' costs some are not never selected, that is fine]
clear,clc
yo=20; %Number of Years considered
gro=.01; %Growth of demand
int=.05; %Interest rate of money
ABudg=3E9; %Annual Budget
%Legend for conservation options
LegOpt={'Purchased', 'Toilets', 'Catchment', 'Fallowed','Rotated'};
j=[-4.5,-.03, -.01,-4,-2]; %Conservation Savings (ac-ft/y)
c=[1,1,1,0,0]; %Which Options are propetual Conservation 1/0 y/n
F=[20000, 150, 100, 950,300]; %Conservation Cost ($)
ub=repmat([inf,10000,10000,inf,inf],1,yo);
%annual limits to purchase options
c=j.*c;
opt=length(j);
o=zeros(1,opt); %Counting and manipulation
for i=1:yo %Creating the 'A' Matrix
A(i,:)=[repmat(c,1,i-1),j,repmat(o,1,yo-i)];
end
f=zeros(yo,opt);
b=zeros(1,yo);
b(1)=1200000;
f(1,:)=F;
for i=2:yo %Compound Interest for Costs, Demand
f(i,:)=f(i-1,:)*(1+int);
b(i)=b(i-1)*(1+gro);
end
f=reshape(f',1,[])';
value=repelem(eye(yo),1,opt).*f';
aBudg=repmat(ABudg,1,yo);
lb=zeros(1,yo*opt);
[x of]=linprog(f,[A;value],[-b,aBudg],[],[],lb,ub);
volum=reshape(x,opt,yo); %How much of each option selected each year
ACost=value*x; %Annual Cost of options selected
sum(ACost) %Total Outlay
figure(2)
for i=1:opt
plot(1:yo,volum(i,:)); hold on
end
legend(LegOpt)
xlim([1,yo])
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回答 (1 件)
Varun
2023 年 4 月 18 日
Hello William!
As per my understanding, you want to introduce new variables to your linear programming mechanism and expand its dimensionality to 3D. While I am not sure about exactly what results are expected from this analysis, I believe this sample plot (attached below) is similar to what you may be looking for:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1359778/image.png)
Regarding the 3D plot, MATLAB has ready-to-go functions which you can use such as ‘plot3’. You may find the documentation for the same at https://www.mathworks.com/help/matlab/ref/plot3.html .
As for introducing the new variables, I think you’ll have to solve the system of equations for all existing variables repeatedly, each time the budget changes. You can store this new data generated as a cell array. Cell arrays are equipped to contain entire matrices in a single cell, so you don’t have to worry about merging/ appending your existing matrices with new data from the next iteration. You may find the relevant documentation here: https://www.mathworks.com/help/matlab/ref/cell.html.
Hope this helps!
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