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How to subset the matrix/array with shape file?

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Shakir Hussain
Shakir Hussain on 26 Jun 2018
Commented: Adi Mulsandi on 22 Oct 2020
I have matrix of 890*751 and array 890*751*5 and I want to clip/crop/subset this matrix and array with shape file. The shape file is consist on several sub-polygon inside. Each inside sub-polygon of shape file has to clip/crop/subset separately and save with unique name. E.g, we have a shape file with 4 sub-polygon (with name (a,b,c,d) and we have to get 4 clip/crop/subset(a,b,c,d) of the matrix/array with. we can read the shape file by
area = shaperead('shapefile', 'UseGeoCoords', true);
geoshow( area , 'Facecolor', 'blue')
but no idea how to crop/clip/subset the matrix/array. The sample testmatrix, testarray and shapefile are attached here for easy to understand the question. Thank you in advance for any helpe/guide

Accepted Answer

KSSV
KSSV on 26 Jun 2018
Edited: KSSV on 26 Jun 2018
Check this link for a similar question. You can follow the same code.
shapefile = 'shapefile.shp' ;
S = shaperead(shapefile) ;
N = length(S) ;
for i = 1:N
plot(S(i).X,S(i).Y)
hold on
end
lon = load('testlon.mat') ; lon = lon.testlon ;
lat = load('testlat.mat') ; lat = lat.testlat ;
[X,Y] = meshgrid(lon,lat) ;
data = load('testarray.mat') ; data = data.testarray ;
[nx,ny,d] = size(data) ;
%%Extract data
iwant = cell(d,N) ;
for i =1:d
A = data(:,:,i) ;
for j = 1:N
idx = inpolygon(X(:),Y(:),S(i).X,S(i).Y) ;
iwant{i,j} = A(idx) ;
end
end
  10 Comments
Adi Mulsandi
Adi Mulsandi on 22 Oct 2020
Hi Shakir Hussain can you share how to convert the result (iwant) into 2d matrix according to the polygon extend?

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