MATLAB: Appending vectors in a loop

vectors

Data1  =
   4
   5
   6
   7
   8
   9
  10
  11
  12
  -1
   4
   5
   6
   7
   8
   9
  10
  11
  12
  -1
   4
   5
   6
   7
   8
   9
  10
  11
  12
  -1
   4
   5
  6
   7
   8
   9
  10
  11
  12
  -1
Data2= Columns 1 through 2
    [ 4]    [0.0119]   
    [ 5]    [0.0119]   
    [ 6]    [0.0143]   
    [ 7]    [0.0143]
    [ 8]    [0.0187]   
    [ 9]    [0.0256]   
    [10]    [0.0273]   
    [11]    [0.0119]   
    [12]    [0.0143]
I want to be able to take in values from data2 for column 2 using the corresponding values in column 1 and data1 . I would use the following command:
find(ismember(cell2mat(data2),data1)==1);
The problem, if you look closely at the first set, is that there is a -1. I need to force it’s value to be zero. Thus I would have to append the vector.
If the command about is within a loop, how do I append data2 without prompting an error?

Best Answer

out=Data2(ismember(cell2mat(Data2(:,1)),Data1),:)
% to change values of Data1 from -1 to 0
Data1(Data1==-1)=0
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