错误：[fit_resamples()] 的第一个参数应该是模型或工作流

如何解决错误：[fit_resamples()] 的第一个参数应该是模型或工作流

问题：

我正在学习 Julia Silge (link here) 关于使用 tidymodels 和配方的教程。我可以毫无问题地完成大部分工作，但是当我调用 fit_resamples() 函数时出现错误：Error: The first argument to [fit_resamples()] should be either a model or workflow.

我正在为字符复制教程字符中的代码，一切运行正常，包括打印出 validation_splits。但是一旦我调用 fit_resamples()，我就会收到上面的错误 (link to relevant part of tutorial)。如果有用，rlang::last_error() 的输出是：

<error/rlang_error>

The first argument to [fit_resamples()] should be either a model or workflow.
Backtrace:
 
     1. tune::fit_resamples(...)
     2. tune:::fit_resamples.default(...)

有人知道这是怎么回事吗？我该如何解决？我的理解是，我传递给 fit_resamples() 的第一个参数是一个模型，即 character ~ .，并且我已经在脚本的早期将这个相同的模型传递给其他函数而没有问题.有关导致我的机器和 sessionInfo() 出错的代码（和数据），请参见下文。

可重现的示例：

library(tidyverse)

## Bring in data
hotels <- readr::read_csv('https://raw.githubusercontent.com/rfordatascience/tidytuesday/master/data/2020/2020-02-11/hotels.csv')

hotel_stays <- hotels %>% 
  filter(is_canceled == 0) %>% 
  mutate(children = case_when(children + babies > 0 ~ 'children',TRUE ~ 'none'),required_car_parking_spaces = case_when(required_car_parking_spaces > 0 ~ 'parking',TRUE ~ 'none')) %>% 
  select(-is_canceled,-reservation_status,-babies)

hotels_df <- hotel_stays %>% 
  select(children,hotel,arrival_date_month,meal,adr,adults,required_car_parking_spaces,total_of_special_requests,stays_in_week_nights,stays_in_weekend_nights) %>% 
  mutate_if(is.character,factor)

## Build models
library(tidymodels)

set.seed(1234)
hotel_split <- initial_split(hotels_df)
hotel_train <- training(hotel_split)
hotel_test <- testing(hotel_split)

hotel_rec <- recipe(children ~ .,data = hotel_train) %>% 
  step_downsample(children) %>% 
  step_dummy(all_nominal(),-all_outcomes()) %>% 
  step_zv(all_numeric()) %>% 
  step_normalize(all_numeric()) %>% 
  prep()

test_proc <- bake(hotel_rec,new_data = hotel_test)

knn_spec <- nearest_neighbor() %>% 
  set_engine('kknn') %>% 
  set_mode('classification')
knn_fit <- knn_spec %>% 
  fit(children ~ .,data=juice(hotel_rec))
knn_fit

## Evaluate models
set.seed(1234)
validation_splits <- mc_cv(juice(hotel_rec),prop = 0.9,strata = children)
validation_splits

## This is where I get the error
knn_res <- fit_resamples(
  children ~ .,knn_spec,validation_splits,control = control_resamples(save_pred = TRUE)
)

我的sessionInfo()：

> sessionInfo()
R version 4.1.0 (2021-05-18)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS High Sierra 10.13.6

Matrix products: default
BLAS:   /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/4.1/Resources/lib/libRlapack.dylib

Random number generation:
 RNG:     Mersenne-Twister 
 Normal:  Inversion 
 Sample:  Rounding 
 
locale:
[1] en_GB.UTF-8/en_GB.UTF-8/en_GB.UTF-8/C/en_GB.UTF-8/en_GB.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
 [1] GGally_2.1.2.9000  skimr_2.1.3        silgelib_0.1.1     forcats_0.5.1     
 [5] stringr_1.4.0      readr_1.4.0        tidyverse_1.3.1    knitr_1.33        
 [9] yardstick_0.0.8    workflowsets_0.0.2 workflows_0.2.2    tune_0.1.5        
[13] tidyr_1.1.3        tibble_3.1.2       rsample_0.1.0      recipes_0.1.16    
[17] purrr_0.3.4        parsnip_0.1.6      modeldata_0.1.0    infer_0.5.4       
[21] ggplot2_3.3.5      dplyr_1.0.7        dials_0.0.9        scales_1.1.1      
[25] broom_0.7.6        tidymodels_0.1.3  

loaded via a namespace (and not attached):
 [1] colorspace_2.0-1   ellipsis_0.3.2     class_7.3-19       base64enc_0.1-3   
 [5] fs_1.5.0           rstudioapi_0.13    listenv_0.8.0      furrr_0.2.3       
 [9] farver_2.1.0       prodlim_2019.11.13 fansi_0.5.0        lubridate_1.7.10  
[13] xml2_1.3.2         codetools_0.2-18   splines_4.1.0      jsonlite_1.7.2    
[17] pROC_1.17.0.1      dbplyr_2.1.1       shiny_1.6.0        compiler_4.1.0    
[21] httr_1.4.2         backports_1.2.1    assertthat_0.2.1   Matrix_1.3-3      
[25] fastmap_1.1.0      cli_2.5.0          later_1.2.0        htmltools_0.5.1.1 
[29] prettyunits_1.1.1  tools_4.1.0        igraph_1.2.6       gtable_0.3.0      
[33] glue_1.4.2         Rcpp_1.0.6         cellranger_1.1.0   DiceDesign_1.9    
[37] vctrs_0.3.8        iterators_1.0.13   timeDate_3043.102  gower_0.2.2       
[41] xfun_0.23          globals_0.14.0     rvest_1.0.0        mime_0.10         
[45] lifecycle_1.0.0    kknn_1.3.1         future_1.21.0      MASS_7.3-54       
[49] ipred_0.9-11       hms_1.1.0          promises_1.2.0.1   parallel_4.1.0    
[53] RColorBrewer_1.1-2 yaml_2.2.1         curl_4.3.1         rpart_4.1-15      
[57] reshape_0.8.8      stringi_1.6.2      foreach_1.5.1      lhs_1.1.1         
[61] lava_1.6.9         repr_1.1.3         rlang_0.4.11       pkgconfig_2.0.3   
[65] evaluate_0.14      lattice_0.20-44    htmlwidgets_1.5.3  labeling_0.4.2    
[69] tidyselect_1.1.1   parallelly_1.26.0  plyr_1.8.6         magrittr_2.0.1    
[73] R6_2.5.0           generics_0.1.0     DBI_1.1.1          pillar_1.6.1      
[77] haven_2.4.1        withr_2.4.2        survival_3.2-11    nnet_7.3-16       
[81] modelr_0.1.8       crayon_1.4.1       utf8_1.2.1         rmarkdown_2.8     
[85] progress_1.2.2     grid_4.1.0         readxl_1.3.1       reprex_2.0.0      
[89] digest_0.6.27      xtable_1.8-4       httpuv_1.6.1       GPfit_1.0-8       
[93] munsell_0.5.0 

解决方法

您正在查看的博文相当陈旧，其中有一个 change to tune a while back，因此您现在应该首先放置工作流或模型。因此错误消息：

[fit_resamples()] 的第一个参数应该是模型或工作流。

解决方法是将您的模型或工作流作为第一个参数，如下所示：

knn_res <- fit_resamples(
  knn_spec,children ~ .,validation_splits,control = control_resamples(save_pred = TRUE)
)