How to keep only the rows with a minimum value in a specific coloumn but with the same "date" value?

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Marcell Szántó 2018-10-28

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编辑： jonas 2018-10-28

It's hard to properly draw up my problem, but here's an example: I have a table:

where the first three coloumn marks the [hours minutes seconds] and the last one is a specific [value]. Now I would like to keep just one record/row at one second, and not just a random one, but the one with the smallest value in the fourth coloumn. So the final result would be:

 A=[
 10 00 00 3.25
 10 00 40 1.85
 10 01 12 2.45
 ]

Please note that the time of the record is not continous, and the values in the fourth coloumn are not necessary in an ascending order. Thank you in advance for any help!

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Answer 1

jonas 2018-10-28

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编辑：jonas 2018-10-28

在 MATLAB Online 中打开

t = duration(A(:,1),A(:,2),A(:,3))
TT = timetable(t,A(:,end))
TT2 = retime(TT,unique(TT.t),'min')

TT2 =

3×1 timetable
       t        Var1
    ________    ____
    10:00:00    3.25
    10:00:40    1.85
    10:01:12    2.45

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Marcell Szántó 2018-10-28

Thank you very much, it is working pretty well! I wasn't thinking about using timetables.

jonas 2018-10-28

编辑：jonas 2018-10-28

My pleasure! It would be equally easy to solve with grouping methods such as varfun or findgroups / splitapply, but I would strongly recommend using datetime regardless of method.

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