Inconsistent targets when after rerunning a plan, after changing dynamically crossed variables

[psadil]

Prework

• Read and abide by drake's code of conduct.
• Search for duplicates among the existing issues, both open and closed.
• Advanced users: verify that the bug still persists in the current development version (i.e. remotes::install_github("ropensci/drake")) and mention the SHA-1 hash of the Git commit you install.

Description

When a plan that uses the dynamic cross transformation is rerun -- and on the second run there are fewer variables to cross -- the resulting targets are incorrect

Reproducible example

Lightly modified from the drake book's dynamic cross example

library(drake)
plan <- drake_plan(
  numbers = c(1,2),
  letters = c("a", "b"),
  combo = target(
    paste0(numbers, letters), 
    dynamic = cross(numbers, letters))
)
make(plan)
#> ▶ target numbers
#> ▶ target letters
#> ▶ dynamic combo
#> > subtarget combo_5268eea9
#> > subtarget combo_43dd82ac
#> > subtarget combo_07e5554d
#> > subtarget combo_7fa427e0
#> ■ finalize combo
readd(combo)
#> [1] "1a" "1b" "2a" "2b"

# modify plan, removing middle number
plan <- drake_plan(
  numbers = c(1),
  letters = c("a", "b"),
  combo = target(
    paste0(numbers, letters), 
    dynamic = cross(numbers, letters))
)
make(plan)
#> ▶ target numbers
#> ■ finalize combo
readd(combo)
#> [1] "1a" "2a"

^{Created on 2020-03-05 by the reprex package (v0.3.0)}

Session info

devtools::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#>  setting  value                       
#>  version  R version 3.6.1 (2019-07-05)
#>  os       Ubuntu 18.04.4 LTS          
#>  system   x86_64, linux-gnu           
#>  ui       X11                         
#>  language (EN)                        
#>  collate  en_US.UTF-8                 
#>  ctype    en_US.UTF-8                 
#>  tz       America/New_York            
#>  date     2020-03-05                  
#> 
#> ─ Packages ───────────────────────────────────────────────────────────────────
#>  package     * version     date       lib source                         
#>  assertthat    0.2.1       2019-03-21 [1] CRAN (R 3.6.0)                 
#>  backports     1.1.5       2019-10-02 [1] CRAN (R 3.6.1)                 
#>  base64url     1.4         2018-05-14 [1] CRAN (R 3.6.0)                 
#>  callr         3.4.2       2020-02-12 [1] CRAN (R 3.6.1)                 
#>  cli           2.0.2       2020-02-28 [1] CRAN (R 3.6.1)                 
#>  crayon        1.3.4       2017-09-16 [1] CRAN (R 3.6.0)                 
#>  desc          1.2.0       2018-05-01 [1] CRAN (R 3.6.0)                 
#>  devtools      2.2.2       2020-02-17 [1] CRAN (R 3.6.1)                 
#>  digest        0.6.25      2020-02-23 [1] CRAN (R 3.6.1)                 
#>  drake       * 7.11.0.9000 2020-03-05 [1] Github (ropensci/drake@a628f6c)
#>  ellipsis      0.3.0       2019-09-20 [1] CRAN (R 3.6.1)                 
#>  evaluate      0.14        2019-05-28 [1] CRAN (R 3.6.0)                 
#>  fansi         0.4.1       2020-01-08 [1] CRAN (R 3.6.1)                 
#>  filelock      1.0.2       2018-10-05 [1] CRAN (R 3.6.1)                 
#>  fs            1.3.2       2020-03-05 [1] CRAN (R 3.6.1)                 
#>  glue          1.3.1       2019-03-12 [1] CRAN (R 3.6.0)                 
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#>  hms           0.5.3       2020-01-08 [1] CRAN (R 3.6.1)                 
#>  htmltools     0.4.0       2019-10-04 [1] CRAN (R 3.6.1)                 
#>  igraph        1.2.4.2     2019-11-27 [1] CRAN (R 3.6.1)                 
#>  knitr         1.28        2020-02-06 [1] CRAN (R 3.6.1)                 
#>  magrittr      1.5         2014-11-22 [1] CRAN (R 3.6.0)                 
#>  memoise       1.1.0       2017-04-21 [1] CRAN (R 3.6.0)                 
#>  pillar        1.4.3       2019-12-20 [1] CRAN (R 3.6.1)                 
#>  pkgbuild      1.0.6       2019-10-09 [1] standard (@1.0.6)              
#>  pkgconfig     2.0.3       2019-09-22 [1] standard (@2.0.3)              
#>  pkgload       1.0.2       2018-10-29 [1] CRAN (R 3.6.0)                 
#>  prettyunits   1.1.1       2020-01-24 [1] CRAN (R 3.6.1)                 
#>  processx      3.4.2       2020-02-09 [1] CRAN (R 3.6.1)                 
#>  progress      1.2.2       2019-05-16 [1] CRAN (R 3.6.0)                 
#>  ps            1.3.2       2020-02-13 [1] CRAN (R 3.6.1)                 
#>  R6            2.4.1       2019-11-12 [1] CRAN (R 3.6.1)                 
#>  Rcpp          1.0.3       2019-11-08 [1] standard (@1.0.3)              
#>  remotes       2.1.1       2020-02-15 [1] CRAN (R 3.6.1)                 
#>  rlang         0.4.5       2020-03-01 [1] CRAN (R 3.6.1)                 
#>  rmarkdown     2.1         2020-01-20 [1] CRAN (R 3.6.1)                 
#>  rprojroot     1.3-2       2018-01-03 [1] CRAN (R 3.6.0)                 
#>  sessioninfo   1.1.1       2018-11-05 [1] CRAN (R 3.6.0)                 
#>  storr         1.2.1       2018-10-18 [1] CRAN (R 3.6.0)                 
#>  stringi       1.4.6       2020-02-17 [1] CRAN (R 3.6.1)                 
#>  stringr       1.4.0       2019-02-10 [1] CRAN (R 3.6.0)                 
#>  testthat      2.3.2       2020-03-02 [1] CRAN (R 3.6.1)                 
#>  tibble        2.1.3       2019-06-06 [1] CRAN (R 3.6.0)                 
#>  txtq          0.2.0       2019-10-15 [1] CRAN (R 3.6.1)                 
#>  usethis       1.5.1       2019-07-04 [1] CRAN (R 3.6.0)                 
#>  vctrs         0.2.3       2020-02-20 [1] CRAN (R 3.6.1)                 
#>  withr         2.1.2       2018-03-15 [1] CRAN (R 3.6.0)                 
#>  xfun          0.12        2020-01-13 [1] CRAN (R 3.6.1)                 
#>  yaml          2.2.1       2020-02-01 [1] CRAN (R 3.6.1)                 
#> 
#> [1] /home/psadil/R/x86_64-pc-linux-gnu-library/3.6
#> [2] /usr/local/lib/R/site-library
#> [3] /usr/lib/R/site-library
#> [4] /usr/lib/R/library

Expected result

When running the plan the second time, I expected combo to contain "1a" "1b". But rather than dropping the second number, the second letter was dropped.

[wlandau]

Wow, thanks for catching such a serious bug. Should be fixed now in d6f2dde.

[psadil]

Thanks for the fix!