Take coordinate data from struct, throw it into an array. Why is this hard to find info about?

Question

Matthew Powell 2015-2-16

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编辑： Ashish Uthama 2015-2-17

Hi,

I'm working on an image processing program that takes coordinate data of objects in an image acquired via the command regionprops and throws it into an array (that I will grab with a C program).

I'm having no issue sorting singular values into an array, but I am failing to put the coordinate data into one, which looks like [x,y].

code snippet:

blobMeasurements = regionprops(labeledImage, i, 'all');  %labeledImage has object information        
numberOfBlobs = size(blobMeasurements, 1);
Centroid = size(blobMeasurements, ???);
g = 1;
n = 1;
for n = 1:97 
  if (blobMeasurements(n).Area > 500) 
    Centroid(g) = blobMeasurements(n).Centroid;
    g = g + 1;
  end
end

All I need is a simple set of lines that can achieve this. For the record, this isn't a homework assignment.

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Answer 1

Ashish Uthama 2015-2-17

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https://ww2.mathworks.cn/matlabcentral/answers/178775-take-coordinate-data-from-struct-throw-it-into-an-array-why-is-this-hard-to-find-info-about#answer_168301

编辑：Ashish Uthama 2015-2-17

在 MATLAB Online 中打开

Does this help? (If not, use this example code to show how you want your Centriod variable to look like)

stats = regionprops(im2bw(imread('coins.png')),'all');
%%Indices of 'larger' areas 
% The key here is using [] to capture the output of stats.Area into an
% array.
inds = [stats.Area]>1000;
%%Centroids, using logical indexing
% This gives you the data in [x1 y1 x2 y2 ....] format
centroids = [stats(inds).Centroid];

[EDIT - add table syntax] With the latest version, regionprops now supports tables, making it even more easier:

stats = regionprops('table',im2bw(imread('coins.png')),'all');
inds = stats.Area>100;
centroids = stats.Centroid(inds,:);

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Matthew Powell 2015-2-17

Yes that works excellently. I also managed to get it to work by right clicking the struct field to create a cell array, and the function was auto-written at the command line. Much appreciated!

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