Summing up selected row duplicates

Question

I have data that looks like this.

I wish to sum up the value column for rows that have the same name, time, and site. In this case, rows 3 and 4 would be summed, and rows 5 and 7 would be summed up.

I wish for the resulting data frame to look like this.

example data:

    name = c('a', 'a', 'b' , 'b', 'c', 'c', 'c', 'd')
    time = c(1,2,1,1,3,3,3,4)
    site = c('A', 'A', 'A', 'A','B', 'D','B', 'E')
    value = c(5,8,1,0,7,0,8,10)

mock = data.frame(name, time,site,value)

Does this answer your question? [How to sum a variable by group](https://stackoverflow.com/questions/1660124/how-to-sum-a-variable-by-group) — Clemsang, Feb 20 '20 at 15:14

score 1 · Answer 1 · answered Feb 20 '20 at 15:19

I really like the data.table way to do this :

library(data.table)
data[, .(value = sum(value)), by = list(name, time, site)]

   name time site value
1:    a    1    A     5
2:    a    2    A     8
3:    b    1    A     1
4:    c    3    B    15
5:    c    3    D     0
6:    d    4    E    10

The nice thing with data.table is that the order of your rows in the first column isn't change while aggregate() change it.

score 0 · Answer 2 · answered Feb 20 '20 at 15:10

Here's a tidyverse answer:

mock <- mock %>%
  group_by(name, time, site) %>%
  summarize(value = sum(value))

  name   time site  value
  <fct> <dbl> <fct> <dbl>
1 a         1 A         5
2 a         2 A         8
3 b         1 A         1
4 c         3 B        15
5 c         3 D         0
6 d         4 E        10

score 0 · Answer 3 · answered Feb 20 '20 at 15:11

0

You can use base R aggregate to make it, i.e.,

> aggregate(value~.,mock,sum)
  name time site value
1    a    1    A     5
2    b    1    A     1
3    a    2    A     8
4    c    3    B    15
5    c    3    D     0
6    d    4    E    10

answered Feb 20 '20 at 15:11

ThomasIsCoding

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Summing up selected row duplicates

3 Answers3