How to extract data from specific row

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Fouziah Yassin 2023-1-3

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https://ww2.mathworks.cn/matlabcentral/answers/1887917-how-to-extract-data-from-specific-row

评论： Bjorn Gustavsson 2023-1-5

Hi,

I am still new using MATLAB. For your information, I have the data at the workspace (40000 x 7 double) but how can I extract the data at the row with the value of the first column is 1 or 2? Thank you in advance.

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Answer 1

Bjorn Gustavsson 2023-1-3

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编辑：Bjorn Gustavsson 2023-1-3

在 MATLAB Online 中打开

You can do things like this in matlab:

data_oi = data(data(:,1)==1|data(:,1)==2,:);

This wouild give you your data of interest in a variable data_oi where the elements in the first column is either a 1 or a 2. If you're this new to matlab, then one good recommendation is to browse through the on-ramp material - which is a introductory information presentation.

HTH

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Fouziah Yassin 2023-1-4

Many thanks for the answer and it's really helpful. Really appreciate it. I tried it and understood how it worked.

Bjorn Gustavsson 2023-1-5

My pleasure, happy that it helped.

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Answer 2

Mathieu NOE 2023-1-3

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If your data is A , the rows that contains 1 in the first column are defined by ind1

see example below

% dummy data
A = rand(10,10);
A(:,1) = randi(3,10,1); 
% extract data when first column contain 1
ind1 = (A(:,1)==1); % logical index 
A1 = A(ind1,:)  % A extract for first column containing 1's
% extract data when first column contain 2
ind2 = (A(:,1)==2); % logical index 
A2 = A(ind2,:)  % A extract for first column containing 2's