How do I update a struct array in a for loop?

Question

Mark Lepage 2017-9-11

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/356112-how-do-i-update-a-struct-array-in-a-for-loop

编辑： Stephen23 2017-9-12

采纳的回答： Stephen23

在 MATLAB Online 中打开

I am determining the equivalent diameter of circles in a series of images.

My code is as follows:

for k = 1:20
I = imread(k);
BW = im2bw(I);
stats = regionprops(BW,'EquivDiameter');
end

I would like the stats struct array to update the values so I get a summary of all the analyzed equivalent diameters, instead of just the last image which is what my code is giving me now. Any ideas?

Thanks,

Mark

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Stephen23 2017-9-11

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/356112-how-do-i-update-a-struct-array-in-a-for-loop#answer_281116

编辑：Stephen23 2017-9-11

在 MATLAB Online 中打开

Just use indexing to put the data into a non-scalar structure:

stats(k) = ...

4 个评论
显示 2更早的评论隐藏 2更早的评论

Mark Lepage 2017-9-12

编辑：Mark Lepage 2017-9-12

This works well to get all my data into one variable (C{})

So this is an improvement on what I was doing before.

What I am hoping for is that my list generated by stats can be continuously updated with my results as they are generated.

i.e. regionprops generates equivalent diameter values, which will change for every image. I want a single list, that will include the equivalent diameters for every image that is analyzed. Hopefully with the data in one single column.

Your method works well, but each image results are stored in a different column, which will be time consuming to analyze afterwards.

To explain better what I am trying to do, I want to measure the equivalent diameters of bubbles in my images, and then calculate a bubble size distribution from the results of all the images.

Stephen23 2017-9-12

编辑：Stephen23 2017-9-12

在 MATLAB Online 中打开

@Mark Lepage: if the data within C all have suitable sizes, you can certainly concatenate it into one structure afterwards:

cat(N,C{:}) % pick N for the dimension to concatenate along

Note that converting into one structure is a good idea, as it makes accessing the fields very convenient:

https://www.mathworks.com/help/matlab/matlab_prog/access-multiple-elements-of-a-nonscalar-struct-array.html

"To explain better what I am trying to do..."

It really doesn't matter to me if you are measuring bubbles or elephant ears: a cell array is a cell array, and a structure is a structure regardless. If you really wanted help you would give information about your data: what sizes it has, exactly the output you need, and you would upload some samples.

请先登录，再进行评论。