從適合 purrr 的模型中提取殘差

Question

我將我的數據分組並為每組擬合了一個模型，我希望得到每組的殘差。 我可以使用 RStudio 的查看器查看每個模型的殘差，但我不知道如何提取它們。 提取一組殘差可以像diamond_mods[[3]][[1]][["residuals"]] ，但是我如何使用 purrr 從每個組中提取一組殘差（與掃帚一起最終得到一個不錯的小費）？

以下是我已經走了多遠：

library(tidyverse)
library(purrr)
library(broom)


fit_mod <- function(df) {
  lm(price ~ poly(carat, 2, raw = TRUE), data = df)
}

diamond_mods <- diamonds %>%
  group_by(cut) %>%
  nest() %>%
  mutate(
    model = map(data, fit_mod),
    tidied = map(model, tidy)
    #resid = map_dbl(model, "residuals") #this was my best try, it doesn't work
  ) %>%
  unnest(tidied) 

Answer 1

你很接近 - 但你應該使用map()而不是map_dbl()因為你需要返回一個列表而不是一個向量。

diamond_mods <- diamonds %>%
  group_by(cut) %>%
  nest() %>%
  mutate(
    model = map(data, fit_mod),
    tidied = map(model, tidy),
    resid = map(model, residuals)
  ) 

Answer 2

使用dplyr的devel版本，我們可以在按 'cut' 分組后condense執行此操作

library(dplyr)
library(ggplot2)
library(broom)
diamonds %>%
   group_by(cut) %>%
   condense(model = fit_mod(cur_data()),
            tidied = tidy(model), 
            resid = model[["residuals"]])
# A tibble: 5 x 4
# Rowwise:  cut
#  cut       model  tidied           resid         
#  <ord>     <list> <list>           <list>        
#1 Fair      <lm>   <tibble [3 × 5]> <dbl [1,610]> 
#2 Good      <lm>   <tibble [3 × 5]> <dbl [4,906]> 
#3 Very Good <lm>   <tibble [3 × 5]> <dbl [12,082]>
#4 Premium   <lm>   <tibble [3 × 5]> <dbl [13,791]>
#5 Ideal     <lm>   <tibble [3 × 5]> <dbl [21,551]>