insert rows between dates by group

Question

I want to insert rows between two dates by group. My way of doing it is so complicated that I insert missing values by last observation carry forwards and then merge. I was wond

Answer 1

you can try this

library(data.table)
setDT(dt)
tmp <- dt[, .(date = seq.Date(min(date), max(date), by = '1 day')), by = 
'user']
dt <- merge(tmp, dt, by = c('user', 'date'), all.x = TRUE)
dt[, dummy := ifelse(is.na(dummy), 0, dummy)]