Extracting specific data for multiple mat files

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Thanh 2022-8-22

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https://ww2.mathworks.cn/matlabcentral/answers/1783160-extracting-specific-data-for-multiple-mat-files

评论： Chunru 2022-8-24

Hello. I am having around 1800 mat files that are the output of Venlodyne lidar. I have converted all of them to the PCD format as well. So, I want to extract the specific data, which is determined by specific row or column, from those files. Please help me with this question. Thank you so much for your support!

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Chunru 2022-8-22

Attach some sample data.

Thanh 2022-8-22

Sorry for not adding files. Here are some files for instance.

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回答（2 个）

Chunru 2022-8-22

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https://ww2.mathworks.cn/matlabcentral/answers/1783160-extracting-specific-data-for-multiple-mat-files#answer_1030355

在 MATLAB Online 中打开

fn = dir("save*.mat")

fn = 2×1 struct array with fields:

name folder date bytes isdir datenum

for i = 1:length(fn)

matobj{i} = matfile(fn(i).name)

matobj{i}.PCD % Then you can access to any portion of data and assign the results to a variable

end

matobj = 1×1 cell array

{1×1 matlab.io.MatFile}

ans =

pointCloud with properties: Location: [16×1808×3 double] Count: 28928 XLimits: [-10.5304 19.9285] YLimits: [-5.1332 9.1553] ZLimits: [-2.5690 5.3415] Color: [] Normal: [] Intensity: [16×1808 uint8]

matobj = 1×2 cell array

{1×1 matlab.io.MatFile} {1×1 matlab.io.MatFile}

ans =

pointCloud with properties: Location: [16×1808×3 double] Count: 28928 XLimits: [-10.5543 19.8885] YLimits: [-5.1543 9.2809] ZLimits: [-2.5587 5.3218] Color: [] Normal: [] Intensity: [16×1808 uint8]

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Thanh 2022-8-23

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1783160-extracting-specific-data-for-multiple-mat-files#answer_1030885

编辑：Thanh 2022-8-23

在 MATLAB Online 中打开

Thank you SIr for your answer. I tried to use the code to extract data of all mat files in column 1706 but it pops up another error "Index in position 2 exceeds array bounds. Index must not exceed 1." Can you help me with this error please? You can see my code adjustment here. Thank a lots!

fn = dir("save*.mat")
for i = 1:length(fn)
    matobj{i} = matfile(fn(i).name)
    dataPCD = matobj{i}.PCD  % Then you can access to any portion of data and assign the results to a variable
    Data = dataPCD(:,1706)
end