允许参数通过...通过purrr映射通过多个函数的正确方法是什么

Question

请考虑以下三个功能：

f1 <- function(df, ...) {
  df %>%
    mutate(
      model = map(.$splits, ~ f2(.))
    )
}

f2 <- function(split_df) {
  split_df %>%
    analysis() %>% 
    nest() %>%
    mutate(
      forecast = map(data, ~ f3(.$actuals))
    )
}

f3 <- function(x, N = 3, fn = mean, window_size = 6, ...) {
  # stuff
}

我正在较大的管道​​中运行这些功能，但我的问题的要点是：我想将参数传递给f3()（例如，将fn = mean更改为fn = median下面的代码行：

df_resamples %>%
  mutate(
    result = .$resamples %>% map(~ f1(.))
  )

但是，以下两个都不返回正确的结果：

# INCORRECT
df_resamples %>%
  mutate(
    result = .$resamples %>% map(~ f1(.), fn = median)
  )
# ALSO INCORRECT
df_resamples %>%
  mutate(
    result = .$resamples %>% map(~ f1(., fn = median))
  )

如果我在fn中对f2进行硬编码，则会得到正确的结果：

f2_good <- function(split_df) {
  split_df %>%
    analysis() %>% 
    nest() %>%
    mutate(
      forecast = map(data, ~ f3(.$actuals, fn = median))
    )
}

如果我从fn = median传递f3，怎么不能将...传递给f1？

注意：我能够解决将参数传递到f1和f2的问题，但这并不十分干，我想我可以使用省略号来规避这种方法：< / em>

f1 <- function(df, N = 3, fn = mean, window_size = 6) {
  df %>%
    mutate(
      model = map(.$splits, ~ f2(., N = N, fn = fn, window_size = window_size))
    )
}

f2 <- function(split_df, N = 3, fn = mean, window_size = 6) {
  split_df %>%
    analysis() %>% 
    nest() %>%
    mutate(
      forecast = map(data, ~ f3(.$actuals, N = N, fn = fn, window_size = window_size))
    )
}

这样做，我就能做到：

df_resamples %>%
  mutate(
    result = .$resamples %>% map(~ f1(., fn = median))
  )

并获得预期的结果，但是我必须将默认值传递给f1和f2 ...

Answer 1

您是否尝试过将...添加到每个签名和函数调用中，例如：

f1 <- function(df, ...) {
  df %>%
    mutate(
      model = map(.$splits, ~ f2(., ...))
    )
}

f2 <- function(split_df, ...) {
  split_df %>%
    analysis() %>% 
    nest() %>%
    mutate(
      forecast = map(data, ~ f3(.$actuals, ...))
    )
}

f3 <- function(x, N = 3, fn = mean, window_size = 6, ...) {
  # stuff
}

然后致电

df_resamples %>%
  mutate(
    result = .$resamples %>% map(~ f1(., fn = median))
  )

编辑：玩具示例

f1 <- function(x, ...) f2(x, ...)
f2 <- function(x, ...) f3(x, ...)
f3 <- function(x, fn = mean, na.rm = FALSE, ...) fn(x, na.rm = na.rm) 

f1(c(1,2,3,NA), fn = max, na.rm = TRUE)