Aggregate by factor using dplyr

Question

For a sample dataframe comprising a factor:

library(dplyr)
group1 <-c(TRUE, FALSE, FALSE, TRUE, TRUE, FALSE, TRUE, TRUE, FALSE, TRUE, FALSE, FALSE, TRUE, TRUE, FALSE, TRUE, TRUE, FALSE)
variable_a <- c(1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3)
variable_b <- c( 5, 8, 6, 8, 4, 5, 9, 2, 4, 5, 8, 6, 8, 4, 5, 9, 2, 4)

df <- data.frame(group1, variable_a, variable_b)
df$group1 <- as.factor(group1)

I want to use aggregate to summarise by group1:

table_aggregate <- df %>% group_by(group1) %>% 
  summarise(sum_variable_a = sum(variable_a),
            sum_variable_b = sum(variable_b))

How do I tell R I want the sums by TRUE and FALSE and not aggregated together? (i.e. I want the sums of all variable_a and variable_b values for TRUE and FALSE on different rows. Currently I just have '1' in the margins and all the values are summed together).

What is your expected output for this sample input? I'm not sure what you are asking for. What's wrong with the output you get? — MrFlick, Jun 27 '23 at 20:01
Many thanks @stefan_aus_hannover - why can't I group by the TRUES and FALSES in group1? — KT_1, Jun 27 '23 at 20:15

score 1 · Answer 1 · answered Jun 27 '23 at 20:17

as per your code , you are already getting the output as below. Please let me if this is the correct output, if you are looking for a different output then please let me know.

table_aggregate <- df %>% group_by(group1) %>% 
  summarise(sum_variable_a = sum(variable_a),
            sum_variable_b = sum(variable_b)) 

# output 
# A tibble: 2 × 3
  group1 sum_variable_a sum_variable_b
  <fct>           <dbl>          <dbl>
1 FALSE              22             46
2 TRUE               14             56

Many thanks @jkatam - my output is a single dataframe 1 obs of 2 variables, with no group1 (just a '1' in the margins'). I had to run detach(package:plyr) and it works! — KT_1, Jun 27 '23 at 20:22

Aggregate by factor using dplyr

1 Answers1