Expand time interval data into days in R -

suppose have data looks this:

interval_id indiv_id   role start_date   end_date           1        1      2006-05-01 2006-06-16           2        1      b 2006-06-16 2006-10-16           3        1      2006-10-16 2009-10-16           4        1      b 2009-10-16 2014-04-23           5        2      2007-12-15 2009-10-16           6        2      b 2009-10-16 2011-07-01 

but want data looks (taking first role interval example):

interval_id indiv_id   role        day           1        1      2006-05-01           1        1      2006-05-02           1        1      2006-05-03           1        1      2006-05-04           1        1      2006-05-05           1        1      2006-05-06         ...      ...    ...        ...           1        1      2006-06-16 

i'm doing loop in r. pretty sure unnecessary. there package expanding time intervals this? seems reshape-type job since i'm kind of turning time interval long format data set.

thanks.

here's way plyr (assuming, once again, data in df):

library(plyr) byday = ddply(df, .(interval_id, indiv_id, role), transform,                day=seq(as.date(start_date), as.date(end_date), by=1)) 

the start_date , end_date values repeated in every row, can remove if wish.