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

We can use the tidyverse to achieve this task.

library(tidyverse)

dt2 <- dt %>%
  group_by(user) %>%
  do(date = seq(from = min(.$date), to = max(.$date), by = 1)) %>%
  unnest() %>%
  left_join(dt, by = c("user", "date")) %>%
  replace_na(list(dummy = 0)) %>%
  select(colnames(dt))

dt2
# A tibble: 9 x 3
    user dummy       date
        
1      A     1 2017-01-03
2      A     0 2017-01-04
3      A     0 2017-01-05
4      A     1 2017-01-06
5      B     1 2016-05-01
6      B     0 2016-05-02
7      B     1 2016-05-03
8      B     0 2016-05-04
9      B     1 2016-05-05