Fill in missing dates between two sequential dates in R [duplicate]

Question

I'm working with a data set that has a date column in which the date is only recorded when it changes, meaning that any NAs are assumed to be equal to the most recently recorded date. I want to fill in missing dates based on that logic. Here's an example of what the data might look like:

Date	Value
10/2/2015	A1
NA	A2
NA	A3
NA	A4
10/3/2015	B1
NA	B2
NA	B3

And here's the desired result:

Date	Value
10/2/2015	A1
10/2/2015	A2
10/2/2015	A3
10/2/2015	A4
10/3/2015	B1
10/3/2015	B2
10/3/2015	B3

Thanks!

Answer 1

You can use tidyr:

 df %>% 
      tidyr::fill(Date)

or

tidyr::fill(df, Date)

This gives us:

# A tibble: 7 × 2
  Date      Value
  <chr>     <chr>
1 10/2/2015 A1   
2 10/2/2015 A2   
3 10/2/2015 A3   
4 10/2/2015 A4   
5 10/3/2015 B1   
6 10/3/2015 B2   
7 10/3/2015 B3