My interpolation works for one set, but does not work for the other

Hi,

I am using the following code for interpolation from data in files. The problem is that the code runs very nicely in the first set, X1, Y1, while it shows that the X and V values don't have the same length in the second set: X2, Y2. I can't figure out the problem. Both codes present the same type of results and have same column length. The files of both sets are attached herewith.

clear; clc;
y=load ('Y1.txt');
x=load ('X1.txt');
plot(x(:,2),-sum(y(:,2:11),2))

y1=-sum(y(:,2:11),2);
x1=x(:,2);

y3=unique(y1);
x3=unique(x1);

y2 = [1308.9, 2514.9, 4797.9]*1000;
x2 = interp1(y3, x3, y2, 'linear');

figure(1)
plot(x1, y1, '-g')
hold on
plot(x2, y2, 'bp')
hold off
grid
legend('Data', 'Interpolated Points', 'Location', 'NW')

[Ismail Qeshta]

Error message is the following:

Error using interp1>reshapeAndSortXandV (line 423)
X and V must be of the same length.

Error in interp1 (line 92)
[X,V,orig_size_v] = reshapeAndSortXandV(varargin{1},varargin{2});

Error in Interpolate (line 15)
x2 = interp1(y3, x3, y2, 'linear');

Answer 1

[Jan]

The message is clear:

 X and V must be of the same length.

Set a breakpoint in the failing line and check the dimensions:

size(y3)
size(x3)

Or:

y = load('Y2.txt');
x = load('X2.txt');

y1 = -sum(y(:,2:11),2);
x1 = x(:,2);
y3 = unique(y1);
x3 = unique(x1);
size(y3)
size(x3)

 ans =
        5504           1
 ans =
        5501           1

Then an interpolation is not possible. A solution might be:

[x3, ix] = unique(x1);
y3       = y1(ix);

[Ismail Qeshta]

Hi Jan,

Yes. You are right. I have just checked it. Do you have any idea on how to solve this issue? Thanks.

a= size(y3)
b= size(x3)
  a =
          1220           1
  b =
          1215           1

[Ismail Qeshta]

Thank you very much Jan. Your solution worked.