How obtain the Y value that corresponds to the largest X value for a number of plots?

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Hi,
I am trying to write a code that gives me the Y value that corresponds to the largest X value for a number of plots.
I have a code that interpolates X values from Y. I just need the oposite and for the largest X values instead.
clear; clc;
Folder = cd;
N=170;
x2 = zeros(N, 10);
for k = 1:N;
Driftt = sprintf('Disp%d.out', k);
Reactt = sprintf('React%d.out', k);
matDrift = importdata(fullfile(Folder, Driftt));
matReact = importdata(fullfile(Folder, Reactt));
x1= matDrift(:,1);
y1= matDrift(:,2);
[x3, ix] = unique(x1);
y3 = y1(ix);
A=dlmread('Time.txt');
for i=1:size(A,2)
x2 (k,:) = interp1(y3, x3, A(:,i), 'linear');
temp=x2(k,:);
temp(isnan(temp))=0.05;
x2(k,:)=temp;
fid=fopen(['result_' num2str(i) '.txt'],'a');
fprintf(fid,'%f\n',x2(k,:));
fclose(fid);
end

Answers (2)

Yasasvi Harish Kumar
Yasasvi Harish Kumar on 18 Feb 2019
Edited: madhan ravi on 18 Feb 2019
Hey,
I think the following should help. The variable big is an array of the largest x value in each row and the variable bigy is contains corresponding y values.
clear; clc;
Folder = cd;
N=170;
big = zeros(N);
bigy = zeros(N);
x2 = zeros(N, 10);
for k = 1:N;
Driftt = sprintf('Disp%d.out', k);
Reactt = sprintf('React%d.out', k);
matDrift = importdata(fullfile(Folder, Driftt));
matReact = importdata(fullfile(Folder, Reactt));
x1= matDrift(:,1);
y1= matDrift(:,2);
[x3, ix] = unique(x1);
y3 = y1(ix);
A=dlmread('Time.txt');
for i=1:size(A,2)
x2 (k,:) = interp1(y3, x3, A(:,i), 'linear');
temp=x2(k,:);
temp(isnan(temp))=0.05;
x2(k,:)=temp;
for z = 1:10
if x2(k,z)>big(z)
big(z) = x2(k,z);
bigy(z) = A(z,i);
end
end
fid=fopen(['result_' num2str(i) '.txt'],'a');
fprintf(fid,'%f\n',x2(k,:));
fclose(fid);
end
I hope I was of some help.
Regards
  2 Comments
Ismail Qeshta
Ismail Qeshta on 18 Feb 2019
Edited: Ismail Qeshta on 18 Feb 2019
Hi Yasasvi,
Many thanks for your answer and suggested code. I actually keep getting the following error message:
Error using griddedInterpolant
The grid vectors must contain unique points.
Error in interp1 (line 151)
F = griddedInterpolant(X,V,method);
Error in Interpolation (line 44)
x2 (k,:) = interp1(y3, x3, A(:,i), 'linear');
Yasasvi Harish Kumar
Yasasvi Harish Kumar on 18 Feb 2019
To interpolate you will need unique y3 and x3 values. Is there any repeating value in x3 and y3?

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KSSV
KSSV on 18 Feb 2019
Read about the function max
Let X,Y be your data.
[max_x,idx] = max(X) ;
max_y = Y(idx) ;
  7 Comments
Ismail Qeshta
Ismail Qeshta on 18 Feb 2019
Edited: Ismail Qeshta on 18 Feb 2019
Thanks. This is my latest code, but it still does not work. I get all zeroes in my output "Disp.txt" file.
clear; clc;
Folder = cd;
N=170;
x2 = zeros(N, 10);
for k = 1:N;
X = sprintf('SaadC2DynDisp%d.out', k);
Y = sprintf('SaadC2DynReact%d.out', k);
matDrift = importdata(fullfile(Folder, X));
matReact = importdata(fullfile(Folder, Y));
x1= matDrift(:,1);
y1= matDrift(:,2);
[max_x,idx] = max(X) ;
max_y = Y(idx) ;
[x3, ix] = unique(x1);
y3 = y1(ix);
A=dlmread('Time.txt');
fid=fopen(['Disp_' num2str(i) '.txt'],'a');
fprintf(fid,'%f\n',x2(k,:));
fclose(fid);
end

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