how to create a list column of column names where column values are TRUE

debugcn Published at Dev

mac

I've got some survey data for multiple-selection questions that has been output with a column for each possible selection, populated with TRUE/FALSE values, e.g.

library(dplyr)

dat <- tribble(
  ~name, ~state, ~onions, ~`sweet potatoes`, ~garlic,
  "Tom", "WV", TRUE, FALSE, TRUE,
  "Larry", "NC", FALSE, TRUE, FALSE,
  "Beth", "NY", TRUE, TRUE, TRUE
)

dat

#>   name  state onions `sweet potatoes` garlic
#>   <chr> <chr> <lgl>  <lgl>            <lgl> 
#> 1 Tom   WV    TRUE   FALSE            TRUE  
#> 2 Larry NC    FALSE  TRUE             FALSE 
#> 3 Beth  NY    TRUE   TRUE             TRUE

How can I create a list-column containing the column names for which the respondents answered "TRUE"?

simliar to https://stackoverflow.com/a/9508203/1009730

I've tried several variations on the theme of

dat %>%
  rowwise() %>%
  mutate(fav_foods = list(names(which(~ is.logical(.x) && .x))))

which gives the error:

Error: Problem with mutate() input fav_foods. x argument to 'which' is not logical i Input fav_foods is list(names(which(~is.logical(.x) && .x))). i The error occurred in row 1.

tmfmnk

With the addition of purrr, you could do:

dat %>%
 mutate(fav_foods = pmap_chr(across(where(is.logical)), ~ toString(names(c(...))[which(c(...))])))

  name  state onions `sweet potatoes` garlic fav_foods                     
  <chr> <chr> <lgl>  <lgl>            <lgl>  <chr>                         
1 Tom   WV    TRUE   FALSE            TRUE   onions, garlic                
2 Larry NC    FALSE  TRUE             FALSE  sweet potatoes                
3 Beth  NY    TRUE   TRUE             TRUE   onions, sweet potatoes, garlic

Or if you need it as a list:

dat %>%
 mutate(fav_foods = pmap(across(where(is.logical)), ~ names(c(...))[which(c(...))]))

  name  state onions `sweet potatoes` garlic fav_foods
  <chr> <chr> <lgl>  <lgl>            <lgl>  <list>   
1 Tom   WV    TRUE   FALSE            TRUE   <chr [2]>
2 Larry NC    FALSE  TRUE             FALSE  <chr [1]>
3 Beth  NY    TRUE   TRUE             TRUE   <chr [3]>

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