Purrr map multiple functions and two inputs

Question

I am trying to use purrr to map multiple functions to two inputs. An example is given below but ideally i'd like to extend this to more functions. When trying to do this i'm getting an error that the input is not found, however, even when I try and name inputs in the list of functions this doesn't rectify the problem.

library(yardstick)
library(tidyverse)

funcs <- list(accuracy = yardstick::accuracy_vec,
              recall = yardstick::recall_vec)

n <- 1000
x <- as.factor(rbinom(n, 1, 0.5))
y <- as.factor(rbinom(n, 1, 0.5))

df <- tibble(true = rep(list(y), 3),
             preds = rep(list(x), 3))

df
#> # A tibble: 3 x 2
#>   true          preds        
#>   <list>        <list>       
#> 1 <int [1,000]> <int [1,000]>
#> 2 <int [1,000]> <int [1,000]>
#> 3 <int [1,000]> <int [1,000]>

df %>% map2_df(.x = true, .y = preds, .f = funcs)
#> Error in map2(.x, .y, .f, ...): object 'true' not found

funcs <- list(accuracy = ~yardstick::accuracy_vec(truth = .x, estimate = .y),
              recall = ~yardstick::recall_vec(truth = .x, estimate = .y))

df %>% map2_df(.x = true, .y = preds, .f = funcs)
#> Error in map2(.x, .y, .f, ...): object 'true' not found

Ideally I would end up with something like this:

# A tibble: 3 x 4
  true          preds         accuracy recall
  <list>        <list>           <dbl>  <dbl>
1 <int [1,000]> <int [1,000]>      0.7    0.8
2 <int [1,000]> <int [1,000]>      0.7    0.8
3 <int [1,000]> <int [1,000]>      0.7    0.8

Any help is much appreciated, TIA

Answer 1

You can use nested maps:

df %>% 
  mutate(map2_dfr(true, preds, ~map_dfc(funcs, do.call, list(.x, .y))))