Reduce Matrix size with interpolated data arrays

Hi,

I have a 360*720 precipitation matrix with values in milimeter, and i desire a 180*360 matrix with interpolated data to compare my precipitation with other 180*360 data.

here you can see the original 360*720 plot of my data. please help me on this.

Thank you.

Answer 1

[Mathieu NOE]

hello

simply use a 2D interpolation with the appropriate new Xq and Yq vectors

interp2 2-D interpolation (table lookup).

Vq = interp2(X,Y,V,Xq,Yq) interpolates to find Vq, the values of the

underlying 2-D function V at the query points in matrices Xq and Yq.

Matrices X and Y specify the points at which the data V is given.

[Benyamin Nemati]

Thanks for response,

what is V function here ? I just have a matrix and want to reach to another matrix, i dont get the V function.

[Mathieu NOE]

V is not a function, it's the Z values

read the help / doc of interp2

Answer 2

[Jan]

The mean over neighboring rows and columns is smarter than a linear interpolation, which just omits the intermediate rows and columns:

x = rand(360, 720);
y = x(1:2:end, :) + x(2:2:end, :);
z = (y(:, 1:2:end) + y(:, 2:2:end)) / 4;