Dplyr: Alternatives to rowwise

tidyverse
29

OK got it. I add something @hadley cooked up in another channel that is quite nice. He uses list() as the first argument of the pmap_(), instead of ., to select the relevant columns of the data frame. This also means you can re-associate variable names to argument names on-the-fly, as we need to do here.

library(tidyverse)
set.seed(42)

df <- tribble(
  ~groupA, ~groupB, ~v1, ~v2,
  "A","C",4, 1,
  "A","D",2, 3,
  "A","D",1, 5 
)

fun <- function(x, y) {
  val <-  sum(rnorm(10,x,y))
  return(val)
}

df %>% 
  mutate(t = pmap_dbl(list(x = v1, y = v2), fun))
#> # A tibble: 3 x 5
#>   groupA groupB    v1    v2     t
#>   <chr>  <chr>  <dbl> <dbl> <dbl>
#> 1 A      C          4     1 45.5 
#> 2 A      D          2     3 15.1 
#> 3 A      D          1     5  1.10
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