Re: [R] by and by: using two indices in by() or tapply()

Try this: tapply(starttime,list(submitdate, surveyor),min) On Wed, Jun 10, 2009 at 4:20 PM, christiaan pauw wrote: > Hi everyone > I want to apply a function by two indices. > > I have a number of surveyors submitting questionnaires. I want to check the > time of the first submission for the da

[R] by and by: using two indices in by() or tapply()

Hi everyone I want to apply a function by two indices. I have a number of surveyors submitting questionnaires. I want to check the time of the first submission for the day for each surveyor and also see a NA is no submission was done on a particular day. This generates a sample of the data: sta