vctrs
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r-lib
vec_c creates a malformed factor for .ptype = factor()
It only works if all levels are specified
library(vctrs)
str(vec_c("red", "blue", .ptype = factor()))
#> Factor w/ 0 levels: 1 1
str(vec_c(factor("red"), factor("blue"), .ptype = factor()))
#> Factor w/ 0 levels: 1 1
# works
vec_c("red", "blue", .ptype = factor(levels = c("blue", "red")))
#> [1] red blue
#> Levels: blue red
vec_c(factor("red"), factor("blue"))
#> [1] red blue
#> Levels: red blue
Created on 2020-07-16 by the reprex package (v0.3.0)
Session info
devtools::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#> setting value
#> version R version 4.0.1 (2020-06-06)
#> os macOS Catalina 10.15.5
#> system x86_64, darwin17.0
#> ui X11
#> language (EN)
#> collate en_US.UTF-8
#> ctype en_US.UTF-8
#> tz UTC
#> date 2020-07-16
#>
#> ─ Packages ───────────────────────────────────────────────────────────────────
#> package * version date lib source
#> assertthat 0.2.1 2019-03-21 [1] CRAN (R 4.0.0)
#> backports 1.1.8 2020-06-17 [1] CRAN (R 4.0.1)
#> callr 3.4.3 2020-03-28 [1] CRAN (R 4.0.0)
#> cli 2.0.2 2020-02-28 [1] CRAN (R 4.0.0)
#> crayon 1.3.4 2017-09-16 [1] CRAN (R 4.0.0)
#> desc 1.2.0 2018-05-01 [1] CRAN (R 4.0.0)
#> devtools 2.3.0 2020-04-10 [1] CRAN (R 4.0.0)
#> digest 0.6.25 2020-02-23 [1] CRAN (R 4.0.0)
#> ellipsis 0.3.1 2020-05-15 [1] CRAN (R 4.0.0)
#> evaluate 0.14 2019-05-28 [1] CRAN (R 4.0.0)
#> fansi 0.4.1 2020-01-08 [1] CRAN (R 4.0.0)
#> fs 1.4.2 2020-06-30 [1] CRAN (R 4.0.1)
#> glue 1.4.1 2020-05-13 [1] CRAN (R 4.0.0)
#> highr 0.8 2019-03-20 [1] CRAN (R 4.0.0)
#> htmltools 0.5.0 2020-06-16 [1] CRAN (R 4.0.1)
#> knitr 1.29 2020-06-23 [1] CRAN (R 4.0.1)
#> magrittr 1.5 2014-11-22 [1] CRAN (R 4.0.0)
#> memoise 1.1.0 2017-04-21 [1] CRAN (R 4.0.0)
#> pkgbuild 1.1.0 2020-07-13 [1] CRAN (R 4.0.1)
#> pkgload 1.1.0 2020-05-29 [1] CRAN (R 4.0.0)
#> prettyunits 1.1.1 2020-01-24 [1] CRAN (R 4.0.0)
#> processx 3.4.3 2020-07-05 [1] CRAN (R 4.0.0)
#> ps 1.3.3 2020-05-08 [1] CRAN (R 4.0.0)
#> R6 2.4.1 2019-11-12 [1] CRAN (R 4.0.0)
#> remotes 2.1.1 2020-02-15 [1] CRAN (R 4.0.0)
#> rlang 0.4.7 2020-07-09 [1] CRAN (R 4.0.1)
#> rmarkdown 2.3 2020-06-18 [1] CRAN (R 4.0.1)
#> rprojroot 1.3-2 2018-01-03 [1] CRAN (R 4.0.0)
#> sessioninfo 1.1.1 2018-11-05 [1] CRAN (R 4.0.0)
#> stringi 1.4.6 2020-02-17 [1] CRAN (R 4.0.0)
#> stringr 1.4.0 2019-02-10 [1] CRAN (R 4.0.0)
#> testthat 2.3.2 2020-03-02 [1] CRAN (R 4.0.0)
#> usethis 1.6.1 2020-04-29 [1] CRAN (R 4.0.0)
#> vctrs * 0.3.2 2020-07-15 [1] CRAN (R 4.0.1)
#> withr 2.2.0 2020-04-20 [1] CRAN (R 4.0.0)
#> xfun 0.15 2020-06-21 [1] CRAN (R 4.0.1)
#> yaml 2.2.1 2020-02-01 [1] CRAN (R 4.0.0)
#>
#> [1] /Library/Frameworks/R.framework/Versions/4.0/Resources/library
This usage is undefined behaviour at the moment. We treat empty parameterised types as templates in some cases (e.g. data.frame()), but we haven't come up with a general principle for this yet.
Okay, I think an informative error message would be great. Otherwise one gets an error message that doesn't really help e.g. in tidyr
library(tidyr)
tibble(metadata = list(list(name = "nemo"))) %>%
unnest_wider(metadata, ptype = list(name = factor()))
#> Error in as.character.factor(x): malformed factor
Created on 2020-07-16 by the reprex package (v0.3.0)
For tidyr I recommend using the new .transform argument with tried and trusted functions like as.factor() or as.double() by the way.
This currently works as expected, but hopefully we'll be able to do better in the future. Closing for now.