check if value exists in group, set this value, if value does not exist, set another value-CodePudding

I have an example df:

df <- data.frame(
  group = c("a", "a", "a", "a", "b", "b", "c", "c", "c", "c", "d", "d", "d"),
  col1 = c(-36,10,-5,1, 0, 5,10, 5, 20, 2, -1, 1, 2 )
)
   group col1
1      a  -36
2      a   10
3      a   -5
4      a    1
5      b    0
6      b    5
7      c   10
8      c    5
9      c   20
10     c    2
11     d   -1
12     d    1
13     d    2

and I want to derive flag such that grouped by 'group', if there is a value of 1 in col1, set flag = Y. If there is not a value of 1 in col1, then set the highest col1 value to flag = Y.

I tried this logic but I don't know how to make it so that if it meets the first condition to not fulfill the second condition in the group:

df <- df %>%
  group_by(group) %>%
mutate(flag = case_when(
  col1 == 1 ~ "Y",
  col1 == max(col1)  ~ "Y",
  TRUE ~ "")
)

expected output:

   group col1 flag
1      a  -36     
2      a   10     
3      a   -5     
4      a    1    Y
5      b    0     
6      b    5    Y
7      c   10     
8      c    5     
9      c   20    Y
10     c    2     
11     d   -1     
12     d    1    Y
13     d    2

CodePudding user response：

One possible solution:

library(dplyr)

df %>%
  group_by(group) %>%
  mutate(flag = if(any(col1==1)) ifelse(col1==1, "Y", "") 
                else ifelse(col1==max(col1), "Y", ""))

# A tibble: 13 x 3
# Groups:   group [4]
   group  col1 flag 
   <chr> <dbl> <chr>
 1 a       -36 ""   
 2 a        10 ""   
 3 a        -5 ""   
 4 a         1 "Y"  
 5 b         0 ""   
 6 b         5 "Y"  
 7 c        10 ""   
 8 c         5 ""   
 9 c        20 "Y"  
10 c         2 ""   
11 d        -1 ""   
12 d         1 "Y"  
13 d         2 ""

CodePudding user response：

You can try the code below

df %>%
  group_by(group) %>%
  mutate(flag =  ((1:n()) == which.max(2 * (col1 == 1)   (col1 == max(col1))))) %>%
  ungroup()

which gives

# A tibble: 13 × 3
   group  col1  flag
   <chr> <dbl> <int>
 1 a       -36     0
 2 a        10     0
 3 a        -5     0
 4 a         1     1
 5 b         0     0
 6 b         5     1
 7 c        10     0
 8 c         5     0
 9 c        20     1
10 c         2     0
11 d        -1     0
12 d         1     1
13 d         2     0