pmapping by position #experiments

test.r

my_func <- function(alpha, beta, gamma) alpha + beta + gamma

# no
tibble(a = 1:5, b = 6:10, c = 11:15) %>%
  mutate(z = pmap_int(., my_func))

# yes
tibble(a = 1:5, b = 6:10, c = 11:15) %>%
  mutate(z = pmap_int(
    dplyr::select(., alpha = a, beta = b, gamma = c),
    my_func))

# no
list(a = 1:5, b = 6:10, c = 11:15) |>
  pmap_int(my_func)

# no
list(a = 1:5, b = 6:10, c = 11:15) |>
  pmap_int(function(alpha, beta, gamma) alpha + beta + gamma)

# yes
list(x, y, z) |>
  pmap_int(function(first, second, third) (first + third) * second)

# no
list(
  a = list(1, 2, 3, 4, 5),
  b = list(6, 7, 8, 9, 10),
  c = list(11, 12, 13, 14, 15)) |>
  pmap_int(function(first, second, third) (first + third) * second)

# yes! works as long as "columns" are unnamed
list(
  list(1, 2, 3, 4, 5),
  list(6, 7, 8, 9, 10),
  list(11, 12, 13, 14, 15)) |>
  pmap_int(function(first, second, third) (first + third) * second)

# no: can't use mutate on a list, only on a df
tibble(a = 1:5, b = 6:10, c = 11:15) |>
  `class<-`("list") |>
  set_names(NULL) |>
  mutate(.data = _, z = pmap_int(.l = _, my_func))

by_pos <- function(df) {
  df |> `class<-`("list") |> set_names(NULL)
}

# yes!
tibble(a = 1:5, b = 6:10, c = 11:15) %>%
  mutate(z = pmap_int(by_pos(.), my_func))

# yes! (but clunky)
tibble(a = 1:5, b = 6:10, c = 11:15) |>
  (\(df) mutate(df, z = pmap_int(by_pos(df), my_func)))()

# yes! (also clunky)
tibble(a = 1:5, b = 6:10, c = 11:15) |>
  (\(df) mutate(df, z = pmap_int(
    by_pos(df),
    function(alpha, beta, gamma) alpha + beta + gamma)))()

# deliberately returning a list to test list-cols
my_func2 <- function(alpha, beta, gamma) {
  list(paste(as.character(alpha), as.character(beta), as.character(gamma), sep = "-"))
}

# uh, yeah, this is heaps better
tibble(a = 1:5, b = 6:10, c = 11:15) |>
  rowwise() |>
  mutate(z = my_func2(a, b, c))

# jenny's solution
# yes!
tibble(a = 1:5, b = 6:10, c = 11:15) %>%
  mutate(z = pmap_int(
    list(alpha = a, beta = b, gamma = c),
    my_func))

# YES!
tibble(a = 1:5, b = 6:10, c = 11:15) |>
  mutate(z = pmap_int(
    list(alpha = a, beta = b, gamma = c),
    my_func))