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

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 

Answer 1

[Yasasvi Harish Kumar]

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

[Ismail Qeshta]

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]

To interpolate you will need unique y3 and x3 values. Is there any repeating value in x3 and y3?

Answer 2

[KSSV]

Read about the function max

Let X,Y be your data.

[max_x,idx] = max(X) ;
max_y = Y(idx) ;

[Ismail Qeshta]

Thanks KSSV for your comment and suggestion. I am going through it now.

Would it be possible to let me know where shall this be exactly in the code?

[KSSV]

Simple...this should be after variable X,Y are defined and where you want.

[Ismail Qeshta]

Thanks KSSV. I put it the way shown below, but I get 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 21)

x2 (k,:) = interp1(y3, x3, A(:,i), 'linear');

clear; clc;
Folder = cd;
N=170;
x2    = zeros(N, 10);
for k = 1:N;
  X = sprintf('Disp%d.out', k);
  Y  = sprintf('React%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');

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
end

[KSSV]

The error is different......you got the mximum values.......the maximum woul dbe a point..(x,y)...why you want to use it to interp1?? YOu cannot use interp1 like that.......read about intrp1.

[Ismail Qeshta]

Thanks KSSV for your comments and feedback. I will read about intrp1. I am afraid I am finding it difficult to follow up with your suggestions. I hope others here can help me with their suggestions. Thank you again.

[KSSV]

YOu need not to use interp1..you got your maximum vlaues.

[Ismail Qeshta]

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