Is there any R function which can convert binary data to column?

Question

I have a data frame that looks like this:

number	A	B	C	D
0.3	0	1	0	1
0.4	1	1	1	0

and I want to have this data frame:

number	category
0.3	B
0.3	D
0.4	A
0.4	B
0.4	C

Is there any way or function that can help me to do this?

Answer 1

You can use pivot_longer to get the data in long format and filter the values that are not 0.

library(dplyr)
library(tidyr)

df %>%
  pivot_longer(cols = -number, 
               names_to = 'category') %>%
  filter(value != 0) %>%
  select(-value)

# number category
#   <dbl> <chr>   
#1    0.3 B       
#2    0.3 D       
#3    0.4 A       
#4    0.4 B       
#5    0.4 C       

data

It is easier to help if you provide data in reproducible format.

df <- structure(list(number = c(0.3, 0.4), A = 0:1, B = c(1L, 1L), 
    C = 0:1, D = 1:0), row.names = c(NA, -2L), class = "data.frame")

Answer 2

Here is another strategy:

1. assign values to columns with across and case_when
2. remove number column with .keep="unused"
3. remove NA's

library(dplyr)
librayr(tidyr)

df %>% 
    mutate(across(A:D, ~case_when(. == 1 ~ as.numeric(number))), .keep="unused") %>% 
    pivot_longer(
        cols = A:D, 
        names_to = "category",
        values_to = "number"
    ) %>% 
    na.omit()

output:

# A tibble: 5 x 2
  category number
  <chr>     <dbl>
1 B           0.3
2 D           0.3
3 A           0.4
4 B           0.4
5 C           0.4