Including interpolation row by row in a matrix using a for loop

I have a Raman spectral data which contains 140 rows and 1317 columns.

The wavenumbers are in the range of 102-4050 with the resolution of 3.

I want to perform an interpolation to make the data set similar to a calibration data set which the

wavenumbers are in the range of 300-3425.

I have used interp1 as follow:

X = Ramandata 
Wave_no_X = linspace(102,4050,1317);
Wave_no_intrest = linspace(300,3425,1000);
Interpolated = interp1(Wave_no_X, X, Wave_no_intrest);

However this would not work because X should only be a column vector X(1,:).

Therefore I tried a loop to pass all the rows of X through interp1. But the codeis not working. Could any one help?

[n,m] = size(X)

Interpolated = []
for i = 1: n
    
   Interpolated(i) = interp1(Wave_no_X, (X(i,:)), Wave_no_intrest);
    
    
end

Answer 1

[dpb]

What error? Looks like should be ok but didn't have data to try and didn't make up any...but should be able to use the vectorized form here

Wave_no_X = linspace(102,4050,1317);
Wave_no_intrest = linspace(300,3425,1000);
Interpolated = interp1(Wave_no_X, Ramandata.', Wave_no_intrest);

would give the interpolated array

A sample just random data of the same idea --

>> interp1(1:10,rand(10,3),3:9)
ans =
    0.6845    0.3365    0.9711
    0.7025    0.6972    0.7023
    0.9285    0.4717    0.9040
    0.1740    0.3085    0.3593
    0.9693    0.1514    0.0041
    0.7826    0.2067    0.9643
    0.4238    0.1314    0.2428
>> 

NB: the interpolated xq values must be within the range of the x values; interp1 will not extrapolate automatically.

Answer 2

[Cris LaPierre]

You will likely find this example helpful. Just make your X values a column vector. You should transpose your Y values so each row corresponds to X. You can transpose the result back if you prefer to have the columns represent frequency.

X = linspace(102,4050,1317)';
Xq = linspace(300,3425,1000);
Interpolated = interp1(X, Ramandata', Wave_no_intrest)';

Note that this is untested, since you did not share your data.