MATLAB: Down-sampling with interp1

down-samplinginterpolation

Hi,

I have a vector with 1500 rows, and I am trying to down-sample this using interp1 like this:

downsampled = interp1([1:length(original)],original,1:1:100);

However, it looks like the output "downsampled' is just a copy of the first 100 rows of original. Any hints on this?

Cheers

Best Answer

oL = length(original);
downsampled = interp1(1:oL, original, linspace(1,oL,100));

However please think about whether you want 100 points output or 101 points output. If you want to divide into 100 segments of equal length then you want 101 points output.

Related Solutions

MATLAB: How to interpolate the following sample in 200 samples

Let A be your data.

n = length(A) ; 
x = 1:n; 
xi = linspace(1,n,200) ;
Ai = interp1(x,A,xi) ; 
figure
hold on
plot(x,A,'r')
plot(xi,Ai,'b')
legend('original','interpolated')

MATLAB: Downsampling image

Hi, You can use dyaddown() from the Wavelet Toolbox.

    x = randn(8,8);
    % this gives you 1st row, 1st column, 3rd row, 3rd colum, etc
    y = dyaddown(x,'m',1);
    % now this gives you 2nd row, 2nd column, etc
    y = dyaddown(x,'m',0);

Or you can use downsample() from the Signal Processing Toolbox. This gives you one polyphase matrix.

     Y = downsample(x,2,0);
     Y = (downsample(Y',2,0))';

This gives you the other:

       Y1 = downsample(x,2,1);
       Y1 = (downsample(Y1',2,1))';

Hope that helps,

Wayne

Best Answer

Related Solutions

MATLAB: How to interpolate the following sample in 200 samples

MATLAB: Downsampling image

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