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Editorial Team
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Asked: 2026-05-31T00:03:48+00:00

I’m a R beginner and having difficulty with the following pretty simple problem; I

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I’m a R beginner and having difficulty with the following pretty simple problem;
I have the following transaction data:

Data
Row#ID     Lable    Date          Time
4   15275   John    2000-05-16    16:15:00
7   15275   John    2000-05-16    16:25:00
22  15276   Bob     2000-07-04    18:05:00
25  15276   Bob     2000-08-07    05:23:00
10  1234    Kate    2000-06-17    18:07:00
13  1234    Kate    2000-06-21    06:49:00

And need to generate a unique entry for each ID with the minimum Date and minimum Time,
Similar to this:

Row#    ID          Lable   Date        Time
        15275   John        2000-05-16  16:15:00
        15276   Bob         2000-07-04  18:05:00
        1234    Kate        2000-06-17  18:07:00

I have tried 

unique<-aggregate(Date$Date ,list(Data$ID, Data$Time,unique_Data$Lable ), min)

to no avail.

Any assistance would be greatly appreciated.
Thanks

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1 Answer

  1. Editorial Team

    If the Data and Time columns are of class “character” or any other class for which there is a min method (but in particular not if either one is of class “factor) you could use this:

    mins <-aggregate(Data[ , c("Date", "Time")]  ,list(Data$ID) , min)
mins

    Noting that there was a need to cover the class==”factor’ issue, this would have covered even that possibility;

    mins <-aggregate(Data[ , c("Date", "Time")]  ,list(Data$ID) , 
                             function(x) min(as.character(x)) )
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