Obtaining max value from cyclic data

Question

Goutham 2024-1-17

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2071056-obtaining-max-value-from-cyclic-data

评论： Dyuman Joshi 2024-1-17

Reference.xlsx

Hello, I need to obtain the max value of temperature from a cyclic (100 cycles) data. I have tried the following method:

% Start of code

temp_max(:,1) = GetMaxValue(temp,step,3)
function [out] = GetMaxValue(in,step,step_1)
    k = 1;
    for i = 2: length(temp)
        if step(i) == step_1
            out(k) = max(in(i))
            k = k + 1;
        end
    end
end

% end of code

temp is the variable with temperature values and step is the variable of the step numbers. With this code, I am only getting all the values of step 3 as it has nothing to compare the max value against.

Kindly find attached for the excel file with the data. I would request you to help me solve the problem.

Thanks,

Goutham

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Ganesh 2024-1-17

Hi @Goutham,

Do you intend to obtain the maximum temperature from all the data, i.e. the max value of the third column? Or do you intend to obtain the maximum temperature for a particular value of step?

Goutham 2024-1-17

Hello Ganesh,

The attached file consists of 100 cycles worth of test data. I am interested in obtaining the maximum value of temperature (3rd column) at each of those 100 cycles when the step is 3.

Thanks

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Answer 1

Dyuman Joshi 2024-1-17

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2071056-obtaining-max-value-from-cyclic-data#answer_1391626

移动：Dyuman Joshi 2024-1-17

在 MATLAB Online 中打开

Reference.xlsx

For each cycle, finding the maximum of the temperatures corresponding to the step == 3;

%Read the data
T = readtable('Reference.xlsx')
Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.
T = 296017×3 table
    step    CycleNumber     temp 
    ____    ___________    ______

     0           0         23.941
     1           0          24.17
     1           0          24.17
     1           0          24.17
     1           0         24.146
     1           0         24.146
     1           0         24.146
     1           0         24.146
     1           0         24.146
     1           0         24.146
     1           0         24.146
     1           0         24.146
     1           0         24.146
     1           0          24.13
     1           0         24.185
     1           0         24.185
%Values that satisfy the condition
idx = T.step == 3;
%Finding groups accordingly
[grps, cycnum] = findgroups(T.CycleNumber(idx));
%Compute maximum temperature for each group
Temp_max = accumarray(grps, T.temp(idx), [], @max);
%Cycle number and corresponding Max temperature for step value of 3
out = [cycnum Temp_max]
out = 100×2
    1.0000   28.9651
    2.0000   28.9178
    3.0000   28.7285
    4.0000   28.7758
    5.0000   28.7522
    6.0000   28.8626
    7.0000   28.8626
    8.0000   28.8941
    9.0000   29.0598
   10.0000   28.8784

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Goutham 2024-1-17

Thank you for response. It works perfectly.

Dyuman Joshi 2024-1-17

You're welcome!

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Answer 2

Mathieu NOE 2024-1-17

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在 MATLAB Online 中打开

hello

I don't understand your logic ... why do we need to make comparisons with anotehr result ( With this code, I am only getting all the values of step 3 as it has nothing to compare the max value against. )

here's a simple code that will generate two plots

first one is simply to display all temp curves (overlaid) for all cycles
second one will display the max temp of each cycle vs cycle number

hope it helps

data = readmatrix('Reference.xlsx'); % step	 / Cycle Number	/ temp
Cycle_Number = data(:,2);
temp = data(:,3);
CN = unique(Cycle_Number); % get unique values of cycles 
% overlay plot temp (for all cycles) 
figure
hold on
for k = 1:numel(CN)
    ii = Cycle_Number==CN(k); % select data  for cycle number = k
    max_temp(k) = max(temp(ii)); % store max temp of k th cycle
    plot(temp(ii))
end
% plot max_temp vs cycle number 
figure
plot(CN,max_temp)
title('Max Temperature ')
xlabel('Cycle#')
ylabel('Temp')