Error when fitting workflow with `step_dummy()`

[cphaarmeyer]

The problem

I'm having trouble with fitting a model while using step_dummy().

Reproducible example

library(tidymodels)
library(tidyclust)
#> 
#> Attaching package: 'tidyclust'
#> The following objects are masked from 'package:parsnip':
#> 
#>     knit_engine_docs, list_md_problems

data <- tibble(x = factor(c("a", "b")))

spec <- k_means(num_clusters = 2)
rec <- recipe(~., data = data) |> step_dummy(x)
wf <- workflow(rec, spec)

fit(wf, data = data)
#> Error in `unique.default()`:
#> ! unique() applies only to vectors

^{Created on 2026-06-23 with reprex v2.1.1}

Session info

sessioninfo::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#>  setting  value
#>  version  R version 4.5.3 (2026-03-11)
#>  os       Linux Mint 22.3
#>  system   x86_64, linux-gnu
#>  ui       X11
#>  language en_GB
#>  collate  en_US.UTF-8
#>  ctype    en_US.UTF-8
#>  tz       Europe/Berlin
#>  date     2026-06-23
#>  pandoc   3.8.3 @ /usr/share/positron/resources/app/quarto/bin/tools/x86_64/ (via rmarkdown)
#>  quarto   1.9.38 @ /usr/share/positron/resources/app/quarto/bin/quarto
#> 
#> ─ Packages ───────────────────────────────────────────────────────────────────
#>  package      * version    date (UTC) lib source
#>  backports      1.5.1      2026-04-03 [1] RSPM
#>  broom        * 1.0.13     2026-05-14 [1] RSPM
#>  class          7.3-23     2025-01-01 [2] CRAN (R 4.5.3)
#>  cli            3.6.6      2026-04-09 [1] RSPM
#>  codetools      0.2-20     2024-03-31 [2] CRAN (R 4.5.3)
#>  data.table     1.18.4     2026-05-06 [1] RSPM
#>  dials        * 1.4.4      2026-06-22 [1] RSPM
#>  DiceDesign     1.10       2023-12-07 [1] RSPM
#>  digest         0.6.39     2025-11-19 [1] RSPM
#>  dplyr        * 1.2.1      2026-04-03 [1] RSPM
#>  evaluate       1.0.5      2025-08-27 [1] RSPM
#>  farver         2.1.2      2024-05-13 [1] RSPM
#>  fastmap        1.2.0      2024-05-15 [1] RSPM
#>  fs             2.1.0      2026-04-18 [1] RSPM
#>  furrr          0.4.0      2026-03-31 [1] RSPM
#>  future         1.70.0     2026-03-14 [1] RSPM
#>  future.apply   1.20.2     2026-02-20 [1] RSPM
#>  generics       0.1.4      2025-05-09 [1] RSPM
#>  ggplot2      * 4.0.3      2026-04-22 [1] CRAN (R 4.5.3)
#>  globals        0.19.1     2026-03-13 [1] RSPM
#>  glue           1.8.1      2026-04-17 [1] CRAN (R 4.5.3)
#>  gower          1.0.2      2024-12-17 [1] RSPM
#>  gtable         0.3.6      2024-10-25 [1] RSPM
#>  hardhat        1.4.3      2026-04-04 [1] RSPM
#>  htmltools      0.5.9      2025-12-04 [1] RSPM
#>  infer        * 1.1.0      2025-12-18 [1] CRAN (R 4.5.2)
#>  ipred          0.9-15     2024-07-18 [1] RSPM
#>  knitr          1.51       2025-12-20 [1] RSPM
#>  lattice        0.22-9     2026-02-09 [2] CRAN (R 4.5.3)
#>  lava           1.9.1      2026-05-14 [1] RSPM
#>  lifecycle      1.0.5      2026-01-08 [1] RSPM
#>  listenv        1.0.0      2026-06-22 [1] RSPM
#>  lubridate      1.9.5      2026-02-04 [1] CRAN (R 4.5.2)
#>  magrittr       2.0.5      2026-04-04 [1] RSPM
#>  MASS           7.3-65     2025-02-28 [2] CRAN (R 4.5.3)
#>  Matrix         1.7-4      2025-08-28 [2] CRAN (R 4.5.3)
#>  mclust         6.1.2      2025-10-31 [1] RSPM
#>  modeldata    * 1.5.1      2025-08-22 [1] RSPM
#>  modelenv       0.2.0      2024-10-14 [1] RSPM
#>  nnet           7.3-20     2025-01-01 [2] CRAN (R 4.5.3)
#>  otel           0.2.0      2025-08-29 [1] RSPM
#>  parallelly     1.47.0     2026-04-17 [1] CRAN (R 4.5.3)
#>  parsnip      * 1.6.0      2026-05-14 [1] RSPM
#>  pillar         1.11.1     2025-09-17 [1] RSPM
#>  pkgconfig      2.0.3      2019-09-22 [1] RSPM
#>  prodlim        2026.03.11 2026-03-11 [1] RSPM
#>  purrr        * 1.2.2      2026-04-10 [1] RSPM
#>  R6             2.6.1      2025-02-15 [1] RSPM
#>  RColorBrewer   1.1-3      2022-04-03 [1] RSPM
#>  Rcpp           1.1.1-1.1  2026-04-24 [1] RSPM
#>  recipes      * 1.3.3      2026-05-30 [1] RSPM
#>  reprex         2.1.1      2024-07-06 [1] RSPM
#>  rlang          1.2.0      2026-04-06 [1] RSPM
#>  rmarkdown      2.31       2026-03-26 [1] RSPM
#>  rpart          4.1.24     2025-01-07 [2] CRAN (R 4.5.3)
#>  rsample      * 1.3.2      2026-01-30 [1] RSPM
#>  S7             0.2.2      2026-04-22 [1] CRAN (R 4.5.3)
#>  scales       * 1.4.0      2025-04-24 [1] RSPM
#>  sessioninfo    1.2.4      2026-06-04 [1] RSPM
#>  sparsevctrs    0.3.6      2026-01-27 [1] RSPM
#>  survival       3.8-6      2026-01-16 [2] CRAN (R 4.5.3)
#>  tailor       * 0.1.0      2025-08-25 [1] RSPM
#>  tibble         3.3.1      2026-01-11 [1] RSPM
#>  tidyclust    * 0.3.1      2026-06-20 [1] RSPM
#>  tidymodels   * 1.5.0      2026-04-23 [1] CRAN (R 4.5.3)
#>  tidyr        * 1.3.2      2025-12-19 [1] CRAN (R 4.5.2)
#>  tidyselect     1.2.1      2024-03-11 [1] RSPM
#>  timechange     0.4.0      2026-01-29 [1] RSPM
#>  timeDate       4052.112   2026-01-28 [1] RSPM
#>  tune         * 2.1.0      2026-04-17 [1] RSPM
#>  vctrs          0.7.3      2026-04-11 [1] RSPM
#>  withr          3.0.3      2026-06-19 [1] RSPM
#>  workflows    * 1.3.0      2025-08-27 [1] RSPM
#>  workflowsets * 1.1.1      2025-05-27 [1] RSPM
#>  xfun           0.59       2026-06-19 [1] RSPM
#>  yaml           2.3.12     2025-12-10 [1] CRAN (R 4.5.2)
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#> 
#>  [1] /home/philipp/R/x86_64-pc-linux-gnu-library/4.5
#>  [2] /opt/R/4.5.3/lib/R/library
#>  * ── Packages attached to the search path.
#> 
#> ──────────────────────────────────────────────────────────────────────────────

Further investigation reveals that parsnip::maybe_matrix() converts the data to a sparse matrix and hence unique(data) throws an error. The conversion does not happen when calling maybe_matrix(tibble(x_b = 0:1)) directly for some reason.

[EmilHvitfeldt]

yes that definitely looks like a bug, i'll take a look soon and see what i can do