how to find interval of data

Question

elisa ewin 2016-6-3

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/287462-how-to-find-interval-of-data

回答： Elias Gule 2016-6-3

Hi! I have a dataset of trajectories of users: every current location of the traiectories has these fields:_ [userId year month day hour minute second latitude longitude regionId]. Based on the field day, I want to divide trajectories based on daily-scale in interval of different hours: 3 hours, 4 hours, 2 hours. I have realized this code that run for interval of 4 hours

% decomposedTraj is a struct that contains the trajectories based on daily scale
  for i=1:size(decomposedTraj,2)
      if ~isempty(decomposedTraj(i).dailyScaled)
      % find the intervals
      % interval [0-4]hours
      Interval(i).interval_1=(decomposedTraj(i).dailyScaled(:,5)>=0&decomposedTraj(i).dailyScaled(:,5)<4);
      % interval [4-8]hours        
      Interval(i).interval_2=(decomposedTraj(i).dailyScaled(:,5)>=4&decomposedTraj(i).dailyScaled(:,5)<8);
      % interval [8-12]hours 
      Interval(i).interval_3=(decomposedTraj(i).dailyScaled(:,5)>=8&decomposedTraj(i).dailyScaled(:,5)<12);
      % interval [12-16]hours
      Interval(i).interval_4=(decomposedTraj(i).dailyScaled(:,5)>=12&decomposedTraj(i).dailyScaled(:,5)<16);
      % interval [16-20]hours
      Interval(i).interval_5=(decomposedTraj(i).dailyScaled(:,5)>=16&decomposedTraj(i).dailyScaled(:,5)<20);
      % interval [20-0]hours
      Interval(i).interval_6=(decomposedTraj(i).dailyScaled(:,5)>=20);
      end    
  end

or more easily to understand the logic of the code:

A=[22;19;15;15;0;20;22;19;15;15;0;20;20;0;22;21;17;23;22]';
A(A>=0&A<4)
A(A>=4&A<8)
A(A>=8&A<12)
A(A>=12&A<16)
A(A>=16&A<20)
A(A>=20)

It runs and gives the right answer but it's not smart: if I want to change the interval, I have to change all the code... can you help me to find a smart solution more dinamical of this? thanks

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Answer 1

Elias Gule 2016-6-3

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/287462-how-to-find-interval-of-data#answer_224349

在 MATLAB Online 中打开

Will this do:

interval = 2; % 2 hour-interval maxHr = 23; tmstamp = 0 : interval : maxHr; len = length(tmstamp);

Within your loop, add the following loop: A = decomposedTraj(i).dailyScaled(:,5); for index = 2 : len predicate = A >= tmstamp(index-1) & A < tmstamp(index); Interval(i).(sprintf('interval_%d',index-1)) = A(predicate); if index == len Interval(i).(sprintf('interval_%d',index)) = A(A >= tmstamp(end)); end end

Now your code should look like: A. Before the for loop, enter the following lines:

interval = 2;      % 2 hour-interval
maxHr    = 23;
tmstamp = 0 : interval : maxHr;
len     = length(tmstamp);

B. now your loop should be:

% decomposedTraj is a struct that contains the trajectories based on daily scale
for i=1:size(decomposedTraj,2)
    if ~isempty(decomposedTraj(i).dailyScaled)
       % Get data
       A = decomposedTraj(i).dailyScaled(:,5);
       % Update the Interval struct array
       for index = 2 : len
         predicate = A >= tmstamp(index-1) & A < tmstamp(index);
         Interval(i).(sprintf('interval_%d',index-1)) = A(predicate);
         if index == len
           Interval(i).(sprintf('interval_%d',index)) = A(A >= tmstamp(end));
         end
      end
   end    
end