How to perform this for loop for multiple parameter values

Leo Tu

2021 7 7

0 个回答

4 次查看（30 天）

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Temperature.mat

I have the following script and vector of temperatures. I need to run it for parameter values of s=0:1:999, mu=0.1:0.1:100, om=0.01:0.01:10, i.e I need to run the script so many times such that all combinations of the parameters are used. I should end up with 1000^3 nll values stored in an array or table.

If anyone could offer some advice on how to approach this, it would be much appreciated.

% T is temperatures, t = time in days
load("Temperature.mat")
T = T'; % from column vector to row vector
AT = T-min(T); % this is the adjusted positive temperatures
s = 0; % lag in days
mu = 0.1;
om = 0.01; % omega
for t=s+1:length(AT)
k = abs(s:-1:(s-t+1)); 
id=[(t-1):-1:0]+1;
lambda(t) = mu+sum(om.^k.*AT(id))/sum(om.^k);
end
for j=1:length(lambda)
  nll = -sum(j*log(lambda(j)))+sum(lambda(j));
end

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Are Mjaavatten 2021-7-8

在 MATLAB Online 中打开

In line 16, you throw away all results except the last. Should it rather be

nll(j) = -sum(j*log(lambda(j)))+sum(lambda(j));

I think you need to rethink what you want and if you are on the right track. I recommend to start with just one year of data so things are quicker and easier to inspect.

Try to compare results for, say, s = 0 and s = 30 or 180. What do you want to use in your final plot? You surely do not want to plot 12054 x 1000 x 1000 x 1000 data points?

Leo Tu 2021-7-8

编辑：Leo Tu 2021-7-8

在 MATLAB Online 中打开

@Are Mjaavatten This is now my updated code

% parameter values
srange = [0 9];
om = 0.1;
mu = 0.1;
r = mypoiss(5,om,mu);
s = srange(1):srange(2);
nll = zeros(numel(s));
for si = 1:numel(s)
    t = max(srange)+1:numel(AT);
    for ti = 1:numel(t)
        k = abs(s(si):-1:(s(si)-t(ti)+1));
        id = ((t(ti)-1):-1:0)+1;
        lambda(t(ti)) = mu+sum(om.^k.*AT(id))/sum(om.^k);
        % store all the results
    end
    nll(si) = 0;
    nll(si) = nll(si) - (r(ti).*log(lambda(t(ti)))) + (lambda(t(ti)));
end

where I am still loading the temperatures in same as before. r is the function

function r = mypoiss(s,om,mu) 
% output; r is synthetic time series for number of cases
% input; s is lag, om is decay rate, mu is baseline rate
% T is temperatures, t = time in days
load("Temperature.mat")
T = T'; % from column vector to row vector
AT = T-min(T); % this is the adjusted positive temperatures
for t=s+1:length(AT)
k = abs(s:-1:(s-t+1)); 
id=[(t-1):-1:0]+1;
lambda(t) = mu+sum(om.^k.*AT(id))/sum(om.^k);
end
r = poissrnd(lambda);

So now this loops for all values of s from 0 to 9 and gives 10 nll values stored in a 10x10. I now want the parameter s to be from 0 to 60 but mu and om I think I can get away with just 100 equally spaced points for each.

The problem here is that I don't know how I can loop this for all the other parameter values.

An example of what I am looking for is the second plot from here:

https://uk.mathworks.com/help/matlab/ref/surf.html

The axis should be the parameters s, mu, om and the colorbar should be values of nll.

Thank you for your help so far!

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