Extract variable from .mat files

Hello,

I have mutiple .mat files which I am running in a for loop. I want to extract the data from the specific variable of .mat file. I tried .variable commond, but it didnot work. Could you please suggest me which commond will I use in this case?.

Here is the attached code:

S = dir('*.mat');

LT= [];

for i=1:length(S)

disp(S(i).name)

T = readtable((S(i).name.(A));

Where, A is the vaiable from which I want to extract the data and all .mat files are in tabular format.

Br,

Haresh Kumar

[Rik]

What exactly do you want to do?

[Haresh Kumar]

Well, I have data in one variable of table that I want to classify into different groups.

[Haresh Kumar]

I want to read the frrom one specific variable of table (which is in .mat file) and then want to apply the rest of algorithm.

[Stephen23]

"...all .mat files are in tabular format."

Please upload a sample file by clicking the paperclip button.

Answer 1

[Rik]

I think I understand what you mean. You will have to use load to load a variable from a mat file:

S = dir('*.mat');
LT= [];
for n=1:length(S)
    A=load(fullfile(S(n).folder,S(n).name));
    T=A.A;
    %remainder of your code here
    
end

[Haresh Kumar]

Hello,

Thank you for your answer. I am getting this error ''Reference to non-existent field 'folder''' while running your code. I wrote the folder name but it does not work.

Br,

Haresh Kumar

[Rik]

Then you're running an older release of Matlab (or Octave), which you should have mentioned. You can replace that part with the full or relative path to the mat files.

[Stephen23]

@Rik: probably one of those S variables should be renamed.

[Rik]

Thanks for the comment. I guess I shouldn't edit code on autopilot (I always load to S). I'll edit my answer.

Answer 2

[Stephen23]

D = 'absolute/relative path to the folder where the files are saved';
S = dir(fullfile(D,'*.mat'));
for k = 1:numel(S)
    F = fullfile(D,S(k).name);
    T = load(F);
    T.A
end

[Haresh Kumar]

Hi,

I couldnot understand T.A commond, so let's make it simple. There are a number of .matfiles and in each .mat file there are variables. I want to load the data from a specific variable of .mat file and after loading data I want to delete the negative entries.

May be we can arrange a zoom call and I can show you my code which is more simple way of desribing I guess. Do you have any available time?.

Br,

Haresh Kumar

[Stephen23]

"I couldnot understand T.A commond..."

T is a scalar structure containing the data imported from the mat file, where each variable in the mat file is stored in one field of the structure. You wrote in your original question that "...A is the vaiable from which I want to extract the data...", so accordingly I used the field A to access that data. If the variable actually has a different name than what you described in your question, then of course you would have to use that name instead.

[Haresh Kumar]

Hello,

Thank you for providing the breif information about this commond. I also want to delete the -ve entries from variable (A) before applying the rest of code and for that I am using this commond:

K=T.A;

If K <0

K=[]

else

K= K

But it doesnot work. Could you please guide me how can I solve this problem?.

Br,

Haresh Kumar

[Stephen23]

The MATLAB way is to use logical indexing:

K = T.A;
K(K<0) = []