Adding missing date values in a data frame with multiple observation periods

Question

Thanks in advance.

I am trying to add missing date values that were not included in a observation period for three different individuals.

My data look like t

Answer 1

A base R version:

do.call(rbind,
  by(
    PostData,
    PostData$IndID,
    function(x) {
      out <- merge(
        data.frame(
          IndID=x$IndID[1],
          Date=seq.POSIXt(min(x$Date),max(x$Date),by="1 day")
        ),
        x,
        all.x=TRUE
      )
      out$Event[is.na(out$Event)] <- 0
      out
    }  
  )
)

Result:

       IndID       Date Event Number Percent
P01.1    P01 2011-03-04     1      2   0.390
P01.2    P01 2011-03-05     0     NA      NA
P01.3    P01 2011-03-06     0     NA      NA
P01.4    P01 2011-03-07     0     NA      NA
P01.5    P01 2011-03-08     0     NA      NA
P01.6    P01 2011-03-09     0     NA      NA
P01.7    P01 2011-03-10     0     NA      NA
P01.8    P01 2011-03-11     1      2   0.975
<>