Fill down every other row with level above in tidyverse

Question

I'm learning R and am hitting a snag with tidry and dplyr.

I've got a data frame in R where the first column is a factor that only has a level every other row. I'm trying to figure out how to use tidyverse tools to fill down.

I've tried using fill and replace but neither seems to work.

td <- data.frame("State" = c("NY", "", "OH", ""), "Your" = c(101:104), "Name" = c(5:8))

td
State    Your    Name
<fctr>   <int>   <int>
NY       101     5      
         102     6      
OH       103     7      
         104     8  

What I want to get is

State    Your    Name
<fctr>   <int>   <int>
NY       101     5      
NY       102     6      
OH       103     7      
OH       104     8  

using tidyr or dplyr

Answer 1

One option is to replace the blanks ("") with NA (na_if) and use fill from tidyr to fill the NA elements with the non-NA adjacent element before it

library(tidyverse)
td %>% 
   mutate(State = na_if(State, "")) %>%
   fill(State)
#    State Your Name
#1    NY  101    5
#2    NY  102    6
#3    OH  103    7
#4    OH  104    8

---

Or using base R

i1 <- td$State != ""
td$State <- with(td, State[i1][cumsum(i1)])

Answer 2

Solution from zoo

library(zoo)
td[td=='']=NA
zoo::na.locf(td)
  State Your Name
1    NY  101    5
2    NY  102    6
3    OH  103    7
4    OH  104    8