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rgroup-bydata-cleaningdata-wrangling

Adding Id number using group_by() in R

I have a data frame that's formatted like so:

evaluation grouping
1.00 a
0.50 a
2.00 b
1.00 b
2.00 b
0.50 c

I want to create a new column with ID numbers for each grouping like so:

evaluation grouping id
1.00 a 1
0.50 a 1
2.00 b 2
1.00 b 2
2.00 b 2
0.50 c 3

I have attempted this code:

data$id <- data %>% group_by(grouping) %>% 1:nrow(data) %>% ungroup
Solution

  • You can do this without group_by.

    df %>%
  mutate(ID = match(grouping, unique(grouping)))
#>   evaluation grouping ID
#> 1        1.0        a  1
#> 2        0.5        a  1
#> 3        2.0        b  2
#> 4        1.0        b  2
#> 5        2.0        b  2
#> 6        0.5        c  3