R — Expand date range into panel data by group

Question

I have date ranges that are grouped by two variables (id and type) that are currently stored in a data frame called data. My goal is to ex

Answer 1

Here is one way to perform such a transformation using base functions

do.call(rbind,Map(function(id,type,from,to) {
    dts <- seq(from=from, to=to, by="1 day")
    dur <- length(dts)
    data.frame(
        id=rep(id, dur), 
        type=rep(type,dur),
        date=dts
    )
}, data$id, data$type, data$from, data$to))

And the first chunck of the output is

   id type                date
1   1    a 2009-02-21 02:00:00
2   1    a 2009-02-22 02:00:00
3   1    a 2009-02-23 02:00:00
4   1    a 2009-02-25 02:00:00
5   1    b 2009-02-25 02:00:00
6   1    b 2009-02-26 02:00:00
7   1    c 2009-02-26 02:00:00
8   1    c 2009-02-27 02:00:00
9   1    c 2009-02-28 02:00:00
10  1    c 2009-03-01 02:00:00
11  1    b 2009-02-26 02:00:00