reconstruct matrix from vector coordinates
显示 更早的评论
Hello, I have 3 vectors (x,y,data) each equals 1x6358. How can I recreate the matrix DATA based on the indices x and y? Thank you
采纳的回答
Walter Roberson
2017-1-25
Possibly you should be using scatteredInterpolant() or TriScatteredInterp to create an interpolant that you would then sample at points on a 2D grid.
Or possibly you should use
[xu, ~, xuidx] = unique(x);
[yu, ~, yuidx] = unique(y);
nxu = length(xu);
nyu = length(yu);
DATA = accumarray( [xuidx(:), yuidx(:)], data(:) );
This would be primarily for the situation where your x and y values form a grid but not necessarily of integer values and not necessarily equi-distant. This particular form of the code expects that all the x values that are intended to be treated as equal are exactly equal -- for example although 1 and 1-eps both display as 1, they are not exactly equal and this code would treat them as different. (If you do have a grid but the values are not exactly equal then there are ways to deal with that, such as by using uniquetol())
2 个评论
Nicolas
2017-1-25
Walter Roberson
2017-1-25
The nxu and nyu lines above are not needed; I forgot to edit those out. You can get away with
[xu, ~, xuidx] = unique(x);
[yu, ~, yuidx] = unique(y);
DATA = accumarray( [xuidx(:), yuidx(:)], data(:) );
or, if needed, uniquetol() instead of unique()
This would produce a grid that would not necessarily be equally spaced. The vectors xu and yu give the actual coordinates.
If you wanted to create an equally spaced mesh, then probably after the above you would use griddedInterpolant together with a mesh of the points you wanted to sample at.
更多回答（1 个）
sz = [max(x),max(y)];
ix = sub2ind(sz,x,y);
mat = NaN(sz);
mat(ix) = data;
3 个评论
Nicolas
2017-1-25
Walter Roberson
2017-1-25
Your x and y are not indices in the MATLAB sense.
Nicolas
2017-1-25
类别
在 帮助中心 和 File Exchange 中查找有关 Descriptive Statistics 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
