search a particular number in a cell array and return the index of the cell array that is found

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charlie 2011-7-10

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https://ww2.mathworks.cn/matlabcentral/answers/11279-search-a-particular-number-in-a-cell-array-and-return-the-index-of-the-cell-array-that-is-found

评论： Palash Dhande 2020-2-6

Hi guys, thanks for reading. i am new to M, and have a quick question.

I have a cell array, cc.PixelIdxList which is a 1x100 cell array, in each cell it contains a list of numbers. for example:

index 1 contains: 156534 157525 157526 157527 157528

index 2 contains: 157531 157532 157533 157534 157535 157536

I want to use a function to find a number and return the index of the cell in the cc.PixelIdxList.

use=find([cc.PixelIdxList{:}]==157536);

Could anyone give me a hand with this? many thanks.

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singh 2015-4-13

在 MATLAB Online 中打开

my problem is same

if have array which only two columns

    X       Y
2      12.3
443      81.31
23      43.32so on

than how to get index value after find the data

suppose i have X value 21.443 and Y value 81.31

how to get the index value 2

Image Analyst 2015-4-13

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Try something like this

x = xy(:, 1); % Get x alone from the first column
% Find distance of all x from the value 21.443
distances = sqrt(abs(x-21.443));
% Find the index of the closest, the minimum distance
[minDistance, indexOfClosest] = min(distances);

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Answer 1

Oleg Komarov 2011-7-10

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https://ww2.mathworks.cn/matlabcentral/answers/11279-search-a-particular-number-in-a-cell-array-and-return-the-index-of-the-cell-array-that-is-found#answer_15384

在 MATLAB Online 中打开

% Index to the number within the cell

out = cellfun(@(x) find(x == 157536),cc.PixelIdxList,'un',0);

% Index to the cell

idx = cellfun('isempty',out);
find(~idx)

% Pad with zeros the empty cells in the first index

out(idx) = {0}
out = [out{:}];

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charlie 2011-7-10

thank you for your help. I got the following error when trying out the code:

??? The right hand side of this assignment has too few

values to satisfy

the left hand side.

Error in ==> charlie at 54

out{idx} = 0;

Oleg Komarov 2011-7-10

Changed it to:

out(idx) = {0}

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Answer 2

Andrei Bobrov 2011-7-10

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https://ww2.mathworks.cn/matlabcentral/answers/11279-search-a-particular-number-in-a-cell-array-and-return-the-index-of-the-cell-array-that-is-found#answer_15385

在 MATLAB Online 中打开

correct

out = find(~cellfun(@(x)isempty(strfind(x(:)',157536)),cc.PixelIdxList))

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charlie 2011-7-10

thanks for the answer, i got the following error, maybe it is because the content of a cell is not string but a uint16?

??? Error using ==> strfind

Input strings must have one row.

Error in ==> @(x)isempty(strfind(x,157536))

Error in ==> chao at 44

out =

find(~cellfun(@(x)isempty(strfind(x,157536)),cc.PixelIdxList))

>>

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Answer 3

Image Analyst 2011-7-11

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Charlie, I think you're totally taking the wrong approach. PixelIdxList (returned by regionprops) is the linear index (look it up) of a pixel in an image. How would you possibly know to pick a value for it? For example, if PixelIdxList were 517, then that would refer to the element at (2, 2) of a 512x512 image. Let's say that blob #1 contained that pixel. So you're basically asking how you can stick in 517 (which you came up with who-knows-how) and get out 1. I don't think you'd ever do that. Explain what you really want to do. For example do you want to know which blob (region) is the one that contains a particular (x,y) coordinate? Do you want the x,y coordinates themselves instead of the linear indices? If so, ask for PixelList instead of PixelIdxList. I just think you're trying to do some complicated thing to get something that is achieved in a much simpler way, if only you knew more about how regionprops worked.

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Palash Dhande 2020-2-6

Hi Image Analyst,

something you mention in your comment is exactly what I'm trying to achieve.

From the output of bwconncomp, i would like to find the blob inside which a particular (predefined) pixel lies. This pixel is defined by a row and a column.

Any clues how to go about doing this?

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