Edge case: rsplit object fails to store because dim() throws an error

[wlandau]

Prework

• Read and abide by drake's code of conduct.
• Search for duplicates among the existing issues, both open and closed.
• Be considerate of the maintainer's time and make it as easy as possible to troubleshoot any problems you identify. Read here and here to learn about minimal reproducible examples. Format your code according to the tidyverse style guide to make it easier for others to read.

Description

See https://stackoverflow.com/questions/63051383/error-when-using-initial-time-split-with-drake. Apparently drake cannot store rsplit objects because NROW() throws an error.

library(tidyverse)
library(tidymodels)
#> ── Attaching packages ─────────────────────────────────────── tidymodels 0.1.1 ──
#> ✓ broom     0.7.0      ✓ recipes   0.1.13
#> ✓ dials     0.0.8      ✓ rsample   0.0.7 
#> ✓ infer     0.5.3      ✓ tune      0.1.1 
#> ✓ modeldata 0.0.2      ✓ workflows 0.1.2 
#> ✓ parsnip   0.1.2      ✓ yardstick 0.0.7
#> ── Conflicts ────────────────────────────────────────── tidymodels_conflicts() ──
#> x scales::discard() masks purrr::discard()
#> x dplyr::filter()   masks stats::filter()
#> x recipes::fixed()  masks stringr::fixed()
#> x dplyr::lag()      masks stats::lag()
#> x yardstick::spec() masks readr::spec()
#> x recipes::step()   masks stats::step()

generate_data <- function() {
    tibble(x = rnorm(1e5), y = rnorm(1e5))
}

split_the_data <- function(data) {
    data %>% 
        initial_time_split()
}

NROW(split_the_data(generate_data()))
#> Error in UseMethod("complement"): no applicable method for 'complement' applied to an object of class "rsplit"

^{Created on 2020-07-23 by the reprex package (v0.3.0)}

Reproducible example

library(drake)
library(tidyverse)
library(tidymodels)
#> ── Attaching packages ─────────────────────────────────────── tidymodels 0.1.1 ──
#> ✓ broom     0.7.0      ✓ recipes   0.1.13
#> ✓ dials     0.0.8      ✓ rsample   0.0.7 
#> ✓ infer     0.5.3      ✓ tune      0.1.1 
#> ✓ modeldata 0.0.2      ✓ workflows 0.1.2 
#> ✓ parsnip   0.1.2      ✓ yardstick 0.0.7
#> ── Conflicts ────────────────────────────────────────── tidymodels_conflicts() ──
#> x recipes::check()      masks drake::check()
#> x scales::discard()     masks purrr::discard()
#> x tidyr::expand()       masks drake::expand()
#> x dplyr::filter()       masks stats::filter()
#> x recipes::fixed()      masks stringr::fixed()
#> x rsample::gather()     masks tidyr::gather(), drake::gather()
#> x dplyr::lag()          masks stats::lag()
#> x yardstick::spec()     masks readr::spec()
#> x recipes::step()       masks stats::step()
#> x workflows::workflow() masks drake::workflow()

generate_data <- function() {
    tibble(x = rnorm(1e5), y = rnorm(1e5))
}

split_the_data <- function(data) {
    data %>% 
        initial_time_split()
}

plan <- drake_plan(
    data = generate_data(),
    split_data = split_the_data(data)
)

make(plan)
#> ▶ target data
#> ▶ target split_data
#> Error in UseMethod("complement"): no applicable method for 'complement' applied to an object of class "rsplit"

^{Created on 2020-07-23 by the reprex package (v0.3.0)}

The traceback points to NROW(), which apparently fails for rsplit objects.

drake/R/store_outputs.R

Line 240 in fe2a72b

meta$size_vec <- NROW(undecorate_format_value(value))