How to extract data from specific row

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.

Answer 1

[Bjorn Gustavsson]

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

[Fouziah Yassin]

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

[Bjorn Gustavsson]

My pleasure, happy that it helped.

Answer 2

[Mathieu NOE]

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

[Fouziah Yassin]

Thank you for the code with the explanation. It is really useful for me to learn.