Fraction excreted unit conversion - fraction not a recognised unit

[HCollis16]

Hi PKNCA Team,

I am trying to use the unit conversion features in PKNCA but was getting errors related to the fe unit conversion. Taking a step back, I tried to run the code in vignettes/v07-unit-conversions.Rmd and got the same error issue.

The code I am trying to run from the vignette:

suppressPackageStartupMessages(
  library(PKNCA)
)

d_units_auto <- pknca_units_table(concu="ng/mL", doseu="mg", amountu="mg", timeu="hr")
# Show a selection of the units generated
d_units_auto[d_units_auto$PPTESTCD %in% c("cmax", "tmax", "auclast", "cl.obs", "vd.obs"), ]

d_units_clean <-
  pknca_units_table(
    concu="ng/mL", doseu="mg", amountu="ng", timeu="hr",
    conversions=
      data.frame(
        PPORRESU=c("mg/(hr*ng/mL)", "mg/(ng/mL)", "hr", "ng/mg"),
        PPSTRESU=c("L/hr", "L", "day", "fraction")
      )
  )

# Show a selection of the units generated
d_units_clean[d_units_clean$PPTESTCD %in% c("cmax", "tmax", "auclast", "cl.obs", "vd.obs", "fe"), ]

The error I receive:

Error: In ‘fraction’, ‘fraction’ is not recognized by udunits.

See a table of valid unit symbols and names with valid_udunits().
Custom user-defined units can be added with install_unit().

See a table of valid unit prefixes with valid_udunits_prefixes().
Prefixes will automatically work with any user-defined unit.

SessionInfo:

> sessionInfo()
R version 4.4.2 (2024-10-31 ucrt)
Platform: x86_64-w64-mingw32/x64
Running under: Windows 11 x64 (build 22631)

Matrix products: default


locale:
[1] LC_COLLATE=English_United Kingdom.utf8  LC_CTYPE=English_United Kingdom.utf8    LC_MONETARY=English_United Kingdom.utf8
[4] LC_NUMERIC=C                            LC_TIME=English_United Kingdom.utf8    

time zone: Europe/London
tzcode source: internal

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

other attached packages:
[1] PKNCA_0.12.0

loaded via a namespace (and not attached):
 [1] backports_1.5.0   R6_2.5.1          tidyselect_1.2.1  lattice_0.22-6    magrittr_2.0.3    glue_1.8.0        tibble_3.2.1     
 [8] pkgconfig_2.0.3   dplyr_1.1.4       generics_0.1.3    lifecycle_1.0.4   cli_3.6.3         grid_4.4.2        vctrs_0.6.5      
[15] compiler_4.4.2    rstudioapi_0.17.1 tools_4.4.2       checkmate_2.3.2   nlme_3.1-166      pillar_1.10.1     Rcpp_1.0.14      
[22] rlang_1.1.4       units_0.8-7  

Just wondering if this is a bug or if I need to do something to enable the use of the fraction unit. The vignette states: "Loading the PKNCA package adds a unit of "fraction" so that it is usable for fraction excreted (fe)." so I don't think the use of install_unit() should be required.

Appreciate any help!

[billdenney]

That feature is in the development version but not on CRAN yet: https://github.com/humanpred/pknca/blob/fe25af6d7c97093f3ba908231d64c76a2a414fb5/NEWS.md#minor-changes-unlikely-to-affect-pknca-use

To test this, please try the development version of PKNCA.