extract the same coloumn from multiple mtrix

Hi! I'm new here i want to ask if there is a solution in Matlab to extract the same column number from multiple matrix. I have 640 matrix and I want to extract from each mtrix the column indexed 70 and save this column in one new matrix .I thank you in advance for your help

Answer 1

[Matt J]

If your data exists as an MxNx640 array, then it's easy

newmatrix= data(:,70,:);
  newmatrix=reshape(newmatrix,M,640);

[sami]

thank you how can create a MxNx640 array from 640 matrices ?

[Matt J]

We need to know more about the form of your data and how they got that way.

Do you have 640 separate matrix variables in your workspace? If so, how did you create them?

Are the matrices in a cell array A{1}, A{2},...A{640}? If the latter, you can just do

 M=cat(3,A{:})

[sami]

the 640 matrices are 150*19 Double matrices and are named device1_1 to device1_80 device2_2 to device2_80 and so on 8 times

[Matt J]

Sigh... Well, first we'll have to undo the damage. Nothing will be fast until we do:

M=cell(8, 80);

for i=1:8
 for j=1:80

    M{i,j}=eval(['device' num2str(i) '_' num2str(j)]);  

   end
  end

Now you can do as before

 data=cat3(M{:});

newmatrix= data(:,70,:);
  newmatrix=reshape(newmatrix,M,640);

[sami]

Thank you

Answer 2

[Razvan]

To extract column 70 from matrix M you do

C = M(:,70);

To add this column to another matrix (M2) you do

M2 = [M2, C];

[sami]

thank you for your response. I now that but I won't do it manually 640 times. there is no faster solution ?

[Azzi Abdelmalek]

how are named your 640 matrix? , or do you import them each iteration

[sami]

the 640 matrices are 150*19 Double matrices and are named device1_1 to device1_80 device2_2 to device2_80 and so on 8 times

Answer 3

[Azzi Abdelmalek]

M=[] 
for k=1:8
s=['M=[M'   sprintf([',device%d_%d(:,70)'],[k*ones(1,80);(1:80)])  ']']
eval(s)
end