MATLAB: Fill gaps using Nan in for loop

analysisbig datanan valuetime series

I have a time series with some gaps in it and i want to fill the gaps with NaN in loop.
For example, my data is 
data = [0    50;
        1   100;
        2   200;
        3   300;
        5   500;
        6   600;
        7   700;
        10 1000; 
        0    30;
        2    20;
        6    40]
First column and second column refer to time and signal value. But it has 2 objects. (I have thousands objects.). One was begun from 0(first row), the other one was begun 0(9th row). But sometimes it began from 2 or whatever. The solution code should detect the next result when the value of 1st column decreased.
I'd like to change it as a new_data.
new_data = [1   100;
            2   200;
            3   300;
            4   NaN;
            5   500;
            6   600;
            7   700;
            8   NaN;
            9   NaN;
            10 1000;
            0    30;
            1   NaN;
            2    20;
            3   NaN;
            4   Nan;
            5   Nan;
            6    40]
How can I make it?
If anyone can help, it would be greatly appreciated.
Thank you!

Best Answer

Using two accumarray calls:
>> data = [0,50;1,100;2,200;3,300;5,500;6,600;7,700;10,1000;0,30;2,20;6,40]
data =
      0     50
      1    100
      2    200
      3    300
      5    500
      6    600
      7    700
     10   1000
      0     30
      2     20
      6     40
>> D = diff(data(:,1),1,1);
>> F = @(v){(v(1):v(end)).'};
>> M = [cell2mat(accumarray(cumsum([true;D<0]),data(:,1),[],F)),accumarray(cumsum([1;max(1,D)]),data(:,2),[],[],NaN)]
M =
      0     50
      1    100
      2    200
      3    300
      4    NaN
      5    500
      6    600
      7    700
      8    NaN
      9    NaN
     10   1000
      0     30
      1    NaN
      2     20
      3    NaN
      4    NaN
      5    NaN
      6     40
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