Consolidate data in several columns to group by unique value in another column

Question

I am hoping to consolidate data in several columns to group by unique value in another column.

group_id	food_1	food_2	food_3
1	1	0	0
1	0	2	0
1	0	0	6
2	2	0	0
2	0	1	0
2	0	0	5

I would like it be consolidated so it is one row for each group_id.

Answer 1

In base R we can use aggregate: With aggregate we can apply the sum function to each column groupwise:

aggregate(. ~ group_id, df, sum)

the dplyr equivalent would be:

library(dplyr) #>= 1.1.0
df %>% 
  summarise(across(starts_with("food"), ~sum(.)), .by = group_id)

  group_id food_1 food_2 food_3
1        1      1      2      6
2        2      2      1      5