Extracting data from a table(.mat file)

Question

Abhivyakti 2012-7-16

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/43748-extracting-data-from-a-table-mat-file

评论： Walter Roberson 2020-7-15

I have a .mat file which consist of a table( size- 19x3659). I need to extract data from it in the following pattern. Column 1-3 (Then after a gap of 128) Column 129-131 column 385-387....and so on. All the rows are to be considered.

I have no clue about this. New to MATLAB. Any help would be appreciated.

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Abhivyakti 2012-7-16

P.s : I need the extracted data in the form of a table , the way it was earlier with the same rows and selected columns.

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Answer 1

Azzi Abdelmalek 2012-7-16

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https://ww2.mathworks.cn/matlabcentral/answers/43748-extracting-data-from-a-table-mat-file#answer_53704

在 MATLAB Online 中打开

% let us take the random matrix a, 19x3659

 a=rand(19,3659);
[n,m]=size(a);b=1:m;
ind=find(and(mod(b,128)<4,mod(b,128)>0))

%check your indices 1-3 129-131 on ind, the extracted matrix result is:

result=a(:,ind)

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Khan Engr 2020-7-15

Hi Azzi Abdelmalek and Abhivyakti, I read this solution, I think my problem is similar, could you please help in my question posted today that you can read on the link

https://it.mathworks.com/matlabcentral/answers/565292-extracting-data-file-in-workspace-from-a-table-files

Thanks

Walter Roberson 2020-7-15

在 MATLAB Online 中打开

data = cat(1, image_patches,labels);

That code is overwriting all of data each iteration.

It looks to me as if data will not be a vector, but I do not seem to be able to locate any hellopatches() function so I cannot tell what shape it will be. As you are not doing imresize() I also cannot be sure that all of the images are the same size, so I cannot be sure that data will be the same size for each iteration. Under the circumstances you should be considering saving into a cell array.

Note: please do not post the same query multiple times. I found at least 3 copies of your query :(

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Answer 2

Image Analyst 2012-7-16

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/43748-extracting-data-from-a-table-mat-file#answer_53686

编辑：Image Analyst 2012-7-16

在 MATLAB Online 中打开

Something like this (untested):

% Load mat file.
s = load(fullMatFileName);
% Extract the table.  Hopefully it's a numerical array called theTable.
theTable = s.theTable;
% Get columns to extract out
[rows columns] = size(theTable);
columnsToExtract = [];
for c = 1 : 128 : (columns-3)
  % Add these 3 columns.
  columnsToExtract = [columnsToExtract , c, c+1, c+2];
end
% Create the new table.
newTable = theTable(:, columnsToExtract);