How to replace NA with most recent non-NA by group? [duplicate]

Answer 1

Depending upon what you are doing next, you may prefer the data in a nested form.

(nested <- df %>% 
  group_by(name) %>% 
  summarize(
    age = na.omit(age)[1], 
    birthplace = na.omit(birthplace)[1], 
    value = list(value)
  )
)
## # A tibble: 4 x 4
##     name   age birthplace     value
##             
## 1      A    28      city1 
## 2      B    NA      city2 
## 3      C    NA         NA 
## 4      D    53         NA 

If you need to compute on individual values, you can always unnest it later.

nested %>% tidyr::unnest()
## # A tibble: 8 x 4
##     name   age birthplace value
##          
## 1      A    28      city1   100
## 2      A    28      city1   101
## 3      B    NA      city2   102
## 4      B    NA      city2   103
## 5      B    NA      city2   104
## 6      C    NA         NA   105
## 7      D    53         NA   106
## 8      D    53         NA   107