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

library(tidyr)
library(dplyr)

df <- df %>%
  gather(type, count, -id)
df <- df[complete.cases(df),][,-3]
df[order(df$id),]
   id       type
1   1 conditionA
7   2 conditionB
13  3 conditionC
19  4 conditionD
5   5 conditionA