setting up code to run matrix of parameter values

Hi,

I've written the code I've put below to run two functions sequentially. I'm trying to see what the effect of changing the parameters I've made global is on the output of the function, so I'd like to set the code up such that it will run combinations of the parameters' possible values. Preferably, I'd love it if it would run all of the possible permutations at once and put them into a .csv file, but that may be too complicated, so running the combinations in sets put into a .csv file would work well too. I've put all their possible values in matrices below, but I have no idea how to go about setting up a for loop so that it will run permutations of these values. As of now, I can get one set of parameter values to successfully run with the final values of the sets of equations be put into a .csv file. Any help would be much appreciated!

global F_1 F_2 R_R1 R_R2 V_1 V_2

%flow rates
F_1 = 0.25 %[0.25 0.5 1.25 2.5];
F_2 = 0.25 %[0.25 0.5 1.25 2.5]; 

 %resource
R_R1 = 1e-5 %[3e-7 1e-5]; 
R_R2 = 1e-5 %[3e-7 1e-5]; 

%culture vessel volume
V_1 = 0.5 %[0.25 0.5]; 
V_2 = 0.5 %[0.25 0.5]; 

for i=1
    soloalgae
    tworesource_soloalgae_algaedaphnia
end

global equil
csvwrite('MATLAB.csv',equil,0,0)

Answer 1

[Walter Roberson]

global F_1 F_2 R_R1 R_R2 V_1 V_2
global equil

F1list = [0.25 0.5 1.25 2.5];
F2list = [0.25 0.5 1.25 2.5];
R1list = [3e-7 1e-5];
R2list = [3e-7 1e-5];
V1list = [0.25 0.5];
V2list = [0.25 0.5];

[F1grid, F2grid, R1grid, R2grid, V1grid, V2grid] = ...
  ndgrid(F1list, F2list, R1list, R2list, V1list, V2list];

N = numel(F1grid);
equils = cell(N,1);
for K = 1:N
  F_1 = F1grid(K);
  F_2 = F2grid(K);
  R_R1 = R1grid(K);
  R_R2 = R2grid(K);
  V_1 = V1grid(K);
  V_2 = V2grid(K);
  soloalgae
  tworesource_soloalgae_algaedaphnia
  equils{K} = equil;
end

After that the task just becomes one of writing out all the values of the cell matrix equils. You did not indicate the type or shape of equil, and you did not indicate how you wanted the results to be written out relative to each other. (Do the results include the input parameters? If not then you would want the inputs written too so you know what you are looking at.)

csvwrite('MATLAB.csv', cell2mat(equils));

might be enough.

[LS]

This is so great!! Thank you!

As you correctly noted, the only problem I'm having now is how to write the data into a csv file effectively. The results don't include input parameters, so I would need to report it along with the equilibrium results (which are just a series of 7 values from the two functions that are defined in the matrix equil). Is there a way I can make csvwrite include both the input parameters and the equilibrium values? Also, how do I word csvwrite so that it doesn't just overwrite the data every run?

Thank you so much for your help!

[Walter Roberson]

Replace

equils{K} = equil;

with

equils{K} = [F_1,F_2,R_R1,R_R2,V_1,V_2,equil];

There is no apparent way to prevent csvwrite from overwriting the data, so I suggest that you use dlmwrite() directly (csvwrite() calls dlmwrite() to do the actual work) using the '-append' flag of dlmwrite().

[LS]

It's working! Thank you so much!

Answer 2

[Clemens]

I would do that by nested for loops:

global F_1 F_2 R_R1 R_R2 V_1 V_2
global equil
datamat = [];
for F_1 = [0.25 0.5 1.25 2.5]
for F_2 = [0.25 0.5 1.25 2.5]
for R_R1 = [3e-7 1e-5]
for R_R2 = [3e-7 1e-5]
for V_1 = [0.25 0.5]
for V_2 = [0.25 0.5]
  soloalgae
  tworesource_soloalgae_algaedaphnia
  datamat = [datamat;  [F_1,F_2,R_R1,R_R2, V_1,V_2,equil]];
end,end,end,end,end,end

gives you a nice datamat in the format of the penultimate line. Write with

csvwrite('result.csv',datamat)

[LS]

Thank you!! This is also very helpful! But I'm having the same problem with writing the CSV file - after I let the model run a few times, I stop the program to check the CSV file and the only thing in it is one set of parameters. I tried making a little for loop for it, so Matlab would write the data in decreasing rows, but it didn't work:

for i=1:N

csvwrite('MATLAB.csv',datamat, N, 0)

end

[LS]

Never-mind, I got it to work - thank you!!