How do I count certain values within a column of a table?

Question

Maizy Troxell 2022-1-25

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https://ww2.mathworks.cn/matlabcentral/answers/1636095-how-do-i-count-certain-values-within-a-column-of-a-table

评论： Star Strider 2022-1-30

I am currently working on a project that aims to create a program that counts cells on a specific image using image processing. I currently have the image altered so that the cells apear as white circular shapes on a solid black background (pictured below.)

I then used the code:

stats = regionprops('table',WBcells,'Centroid','MajorAxisLength','MinorAxisLength');

which produced the following table:

Now I need to figureout how to count values from the MajorAxisLength Column that are larger than 5 pixels and smaller than 26 pixels. If someone could please help me with this or give suggestions on a better way to count the cells that would be very helpful!

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Answer 1

Star Strider 2022-1-25

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https://ww2.mathworks.cn/matlabcentral/answers/1636095-how-do-i-count-certain-values-within-a-column-of-a-table#answer_881755

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One approach —

MajorAxisLength = 30*rand(15,1)
MajorAxisLength = 15×1
   25.3896
   26.0832
   15.9106
   27.0072
    2.4364
   14.0032
   12.0105
    5.0400
   22.0311
   20.4358
Lv = (MajorAxisLength >= 5) & (MajorAxisLength <= 26)
Lv = 15×1 logical array
   1
   0
   1
   0
   0
   1
   1
   1
   1
   1
MeetCriteria = nnz(Lv)
MeetCriteria = 9
PctMeetCriteria = 100*MeetCriteria/numel(MajorAxisLength)
PctMeetCriteria = 60

See if that produces the desired result.

.

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Maizy Troxell 2022-1-30

This does count all of the cells only 60 out of 173.

Star Strider 2022-1-30

在 MATLAB Online 中打开

It counts all the cells and returns true only for those that meet the criteria. Then, it counts the true values to produce the ‘MeetCriteria’ variable. These can be combined into one line if desired:

MeetCriteria = nnz((MajorAxisLength >= 5) & (MajorAxisLength <= 26))

I kept them separate to demonstrate how the code works. (The ‘PctMeetCriteria’ is supplied to standardise the result.)

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Answer 2

yanqi liu 2022-1-26

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https://ww2.mathworks.cn/matlabcentral/answers/1636095-how-do-i-count-certain-values-within-a-column-of-a-table#answer_882145

在 MATLAB Online 中打开

clc; clear all; close all;

img = imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/873730/image.png');

im = imcrop(img, [88 117 410 318]);

J = rgb2hsv(im);

bw = im2bw(mat2gray(J(:,:,2)), 0.6);

WBcells = imopen(bw, strel('disk', 3));

stats = regionprops(WBcells,'Centroid','MajorAxisLength','MinorAxisLength');

% count values from the MajorAxisLength Column that are larger than 5 pixels and smaller than 26 pixels

ma = cat(1, stats.MajorAxisLength);

ce = cat(1, stats.Centroid);

ind = ma > 5 & ma < 26;

figure;

imshow(im);

hold on;

plot(ce(ind,1), ce(ind,2), 'r*');

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Maizy Troxell 2022-1-30

This works great, however not all of the cells are marked. Also this program does not spit out a final count of the cells which is what I really needed help with.

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