Creating a for loop that Concatinates the outputted matrixes

Hi,

I have a file that is a master file, it just contains other file names. I am trying to get matlab to loop through this file and get the data that I need from each of the files listed in the "master file". Here is my code so far,

[num txt raw]=xlsread('vehicle master file');
for(x=1:length(txt))
  x;
  filename=txt{x};
  [num1 txt1 raw1 = xlsread(filename);
  txtrow7=txt1(32:end,7);
  index1 = find(ismember(txtrow7,'response delay','legacy'));
  num5=num1(32:end,5);
  DR=num1(index1,5);
  %remove NaN
  DR1=Snip(DR,nan);
  %find and remove 10's
  values10=find(DR1==10);
  DR1(values10)=[];
end

contained in the for loop is all the code that I want to do. The "DR1" is a 300x1 matrix. I do not know how do get this script to loop back through and create another final matrix and concatinate them together so after the second file I will have a matrix "DR2" that is 600x1. And so on depending on how many times the loop runs. How would I do this?

Thanks.

Answer 1

[Joseph Cheng]

If the resulting DR1 length for each iteration is variable and you are not concerned about time, you can insert your DR2=[] before the for loop and at end of the for loop you do DR2 = [DR2;DR1]; which will set DR2 as DR2 appended with DR1;

[num txt raw]=xlsread('vehicle master file');
DR2=[];  %creates empty array;
for(x=1:length(txt))
 %%stuff done to get DR1
  DR1(values10)=[];
  DR2=[DR2;DR1]%append DR2 with DR1;  
end

Iteration 1: DR2 is empty so DR2 will be DR1.

Iteration 2: DR2 already has the stuff from previous iteration and then you concatenate old stuff with new.

[Joseph Cheng]

Preallocating the DR2 can be performed as such.

[num txt raw]=xlsread('vehicle master file');
DR2=zeros(300*length(txt),1);
for(x=1:length(txt))
 %%stuff done to get DR1
  DR1(values10)=[];
  DR2((i-1)*300+1:i*300) = DR1;  %if DR1 is always 300 long
end

for different length DR1;

CurrentPos = 1;
DR2=zeros(300*length(txt),1); %pre allocation something representative to your data.
for(x=1:length(txt))
 %%stuff done to get DR1
  DR1(values10)=[];
  DR2(Cpos:Cpos+length(DR1)-1) = DR1;  %if DR1 is always 300 long
  Cpos = Cpos+length(DR1);
end 
DR2(Cpos:end)=[];  %clear out remaining allocated space.

Any of the methods should work.