Finding Max value on peak point of graph (logistics growth model)
2 次查看(过去 30 天)
显示 更早的评论
Nirmal Kishore Janakiraman
2021-3-27
评论: Nirmal Kishore Janakiraman
2021-4-1
Is there a method in matlab where i can find the value of the point in the graph (red arrow) before it plateues. I was thinking of using the gradient function. But unable to get any. Some help please !![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/564261/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/564261/image.png)
2 个评论
dpb
2021-3-27
Have more success if attach the data file, probably, so folks have something to work from.
save the variable and attach the .mat file
采纳的回答
Ananya Tewari
2021-3-30
I understand you want the coordinates of the point after which the graph plateaus. Assuming you are having the data points of the graph, using movmax we can get the desired result.
maxi = movmax(data,[0 2]); % Taking 3 values at a time and finding maximum of them
idx = 0; % this will capture the index after which the graph plateaus
for k = 1:n % where n is number of data points
% when the middle value of the 3 elements is the largest we break the loop
if(maxi(k) == data(k+1))
idx = k;
break;
end
end
3 个评论
Ananya Tewari
2021-3-31
Hi Nirmal,
The ischange() finds abrupt changes in a given data and this function can be leveraged to find the approximate point after which the graph plateaus.A possible workaround is as follows:
data = biomass_conc(1,:) %data-points
x=1:5000
% Find change points
changeIndices = ischange(biomass_conc,'linear','MaxNumChanges',20,...
'SamplePoints',x);
% Display results
clf
plot(x,biomass_conc,'Color',[109 185 226]/255,'DisplayName','Input data')
hold on
% Plot change points
x2 = repelem(x(changeIndices),3);
y = repmat([ylim(gca) NaN]',nnz(changeIndices),1);
plot(x2,y,'Color',[51 160 44]/255,'LineWidth',1,'DisplayName','Change points')
title(['Number of change points: ' num2str(nnz(changeIndices))])
hold off
% The last value of x2 contains the approximate x-coordinate after which
% the graph plateaus
x_dash = x2(end) % x-coordinate
y_dash = biomass_conc(x_dash) % corresponding y-coordinate
更多回答(0 个)
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Loops and Conditional Statements 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!