Remove groups if all NA

January 18, 2023

Let’s say I have a table like so:

df <- data.frame("Group" = c("A","A","A","B","B","B","C","C","C"),
              "Num" = c(1,2,3,1,2,NA,NA,NA,NA))

  Group Num
1     A   1
2     A   2
3     A   3
4     B   1
5     B   2
6     B  NA
7     C  NA
8     C  NA
9     C  NA

In this case, because group C has Num as NA for all entries, I would like to remove rows in group C from the table. Any help is appreciated!

>Solution :

You could group_by on you Group and filter the groups with all values that are NA. You can use the following code:

library(dplyr)
df %>%
  group_by(Group) %>%
  filter(!all(is.na(Num)))
#> # A tibble: 6 × 2
#> # Groups:   Group [2]
#>   Group   Num
#>   <chr> <dbl>
#> 1 A         1
#> 2 A         2
#> 3 A         3
#> 4 B         1
#> 5 B         2
#> 6 B        NA

^{Created on 2023-01-18 with reprex v2.0.2}