R - Convert various dummy/logical variables into a single categorical variable/factor from their name

Question

My question has strong similarities with this one and this other one, but my dataset is a little bit different and I can\'t seem to make those solutions work. Please excuse me i

Answer 1

Try:

library(dplyr)
library(tidyr)

df %>% gather(type, value, -id) %>% na.omit() %>% select(-value) %>% arrange(id)

Which gives:

#  id       type
#1  1 conditionA
#2  2 conditionB
#3  3 conditionC
#4  4 conditionD
#5  5 conditionA

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Update

To handle the case you detailed in the comments, you could do the operation on the desired portion of the data frame and then left_join() the other columns:

df %>% 
  select(starts_with("condition"), id) %>% 
  gather(type, value, -id) %>% 
  na.omit() %>% 
  select(-value) %>% 
  left_join(., df %>% select(-starts_with("condition"))) %>%
  arrange(id)