Isolating segments of data in one column using time integrals from the next column

Hi,

I am trying to find segments of data from intervals of start and stop times. The data is a matrix with data in the first column and time stamps in the second column that correspond to the interval times. I would like to get the data in the first column that corresponds to the time stamps in the second column. I would also like the out put interval (there are multiple intervals, in the samples I provided there are 3) to be that each segment is in a separate matrix row or column or even cell array (any is find I just want them to be separate). I have tried some code but am getting empty cell array outputs:

for i=1:numel(interval(:,1))
 w=interval(i,:);
 output{i}=intersect(data(find(data>=w(1))),data(find(data<=w(2))));
end

I have attached an example of data in a matrix data and intervals in matrix interval. Any help would be wonderful.

Answer 1

[dpb]

Logical addressing to the rescue!!! :)

>> for i=1:length(interval)
     c{i}=data(iswithin(data(:,2),interval(1,1),interval(1,2)),:); 
   end
>> whos c
  Name      Size             Bytes  Class    Attributes
    c         1x3             336180  cell               
  >> c{1}(1:5,:)
ans =
   -0.1134   62.6188
   -0.1084   62.6198
   -0.1103   62.6208
   -0.0544   62.6218
   -0.0191   62.6228
>>

iswithin is my "syntactic sugar" utility routine--

 >> type iswithin
function flg=iswithin(x,lo,hi)
% returns T for values within range of input
% SYNTAX:
%  [log] = iswithin(x,lo,hi)
%      returns T for x between lo and hi values, inclusive

flg= (x>=lo) & (x<=hi);
>>

You can collapse the loop via arrayfun; whether it's any faster or not is probably iff--

>> arrayfun(@(i1,i2) data(iswithin(data(:,2),i1,i2),:), ...
                          interval(:,1),interval(:,2), ...
                          'uniformoutput',0)
ans = 
  [7000x2 double]
  [7000x2 double]
  [7000x2 double]
>>

[Krispy Scripts]

Thank you!! Yes, I figured I need to use logical addressing, but was having problems using it to find corresponding values in a matrix