To crate a 2D lookup table with interpolation for matrix data and to crate a function of (x,y) (inputs) give the output from the matrix

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Dror Malka 2019-8-1

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https://ww2.mathworks.cn/matlabcentral/answers/474413-to-crate-a-2d-lookup-table-with-interpolation-for-matrix-data-and-to-crate-a-function-of-x-y-inpu

评论： John D'Errico 2019-8-4

I have data matrix, for an example:

A=[0,1,2,3,4,5; 2,3,5,6,6;3 3 5 0 9]; % A data matrix.

x=-100:5:100; % x-axis

y=-100:5:100; % y-axis

i want to for any (x,y) value (in the range -100 to 100) to obtain the matrix vaule, so two things need to do covert the index A(i,j) to A(x,y) and to inerpolated between breaking point, for an eaxmple A(1,2.5) .

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Answer 1

KSSV 2019-8-1

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/474413-to-crate-a-2d-lookup-table-with-interpolation-for-matrix-data-and-to-crate-a-function-of-x-y-inpu#answer_385752

在 MATLAB Online 中打开

Read about interp2.

n = 20 ; 
Z = peaks(n) ; 
[X,Y] = meshgrid(1:n,1:n) ; 
[Xi,Yi] = meshgrid(1:0.1:n,1:0.1:n) ; 
Zi = interp2(X,Y,Z,Xi,Yi) ;

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Dror Malka 2019-8-4

Thanks, but i want to get the value of the matrix for each x and y axis, for an exampl if i have two points betwee 0-5, then y=ax+b so it is to define in 1D problem and then for each x to get the y. However in my case, i have 2D so not sure if to do it on both axis (x,y), and then to avarege them, the interp2 just give you a larger samples but not for each x and y locations.

John D'Errico 2019-8-4

That is EXACTLY what interp2 will do. It does not just sample the data. It interpolates the data array at any list of points. And this is exactly what you asked for.

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