Extract and sort size of matrix where in the cell

clc;clear;close all

im= [0     0     0     0     0     0     0     0     0     0
     0     0     1     1     1     1     1     1     0     0
     0     0     1     0     0     0     0     0     0     0
     0     0     1     0     0     0     0     0     0     0
     0     0     1     0     0     0     0     0     0     0
     0     0     1     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     1     1     1     1     1
     0     0     0     0     0     0     0     0     0     0];

cc=bwconncomp(im);


for i=1:cc.NumObjects
CC{i}=cc.PixelIdxList{i}
end

Size=zeros(1,cc.NumObjects);
for j=1:cc.NumObjects

Size(:,i)=size(cell2mat(CC(j)))
end

[Stephen23]

What is the expected output?

[Amir Azadeh Ranjbar]

Hi

I want sort Connected Components by theire Size

[Amir Azadeh Ranjbar]

Find areas that theire size are larger than a specified threshold (threshold for size)

Answer 1

[Arjun]

Hi @Amir Azadeh Ranjbar,

I understand that you want to extract the connected componets in the descending order and also find out the components which are greater than a specific threshold size.

You can refer to the following workflow to achieve this:

• Find out the connected components using "bwconncomp"

cc=bwconncomp(im);

• Get the properties of the connected components using "regionprops"

stats = regionprops(cc, 'Area');

• Extract the sizes of the components

sizes = [stats.Area];

• Sort the components by descending order using "sort"

[sortedSizes, sortedIndices] = sort(sizes, 'descend');

• Specify the threshold and filter accordingly

filteredComponents = sortedIndices(sortedSizes > sizeThreshold);

Following are the documentation links of the functions used for your reference:

• bwconncomp: https://www.mathworks.com/help/releases/R2021a/images/ref/bwconncomp.html
• regionprops: https://www.mathworks.com/help/releases/R2021a/images/ref/regionprops.html
• sort: https://www.mathworks.com/help/releases/R2021a/matlab/ref/sort.html

I hope this will help!