tidypredict_fit errors on use of : in models with stepwise dropped terms #74
Description
I noticed tidypredict_fit is fine with multiple interactions in formulas, but for some reason gives errors for : in isolated x:y interactions of models that have dropped terms.
Here is a reprex using a fully specified interaction formula on mtcars, stepped down with stats::step. tidypredict_fit is fine withthe full model, which includes : terms, but errors on the stepped down model for some reason.
Thanks!
# fit a model with interaction terms, tidypredict is fine with * and : formulat functions
cars_lm <- lm(mpg ~ disp * cyl * hp * gear, data = mtcars)
cars_lm
#>
#> Call:
#> lm(formula = mpg ~ disp * cyl * hp * gear, data = mtcars)
#>
#> Coefficients:
#> (Intercept) disp cyl hp
#> 3.165e+02 2.463e-01 -9.459e+01 -2.305e+00
#> gear disp:cyl disp:hp cyl:hp
#> -7.426e+01 1.779e-01 1.059e-03 5.829e-01
#> disp:gear cyl:gear hp:gear disp:cyl:hp
#> -5.569e-02 2.545e+01 5.652e-01 -1.153e-03
#> disp:cyl:gear disp:hp:gear cyl:hp:gear disp:cyl:hp:gear
#> -5.381e-02 -2.973e-04 -1.534e-01 3.298e-04
tidypredict::tidypredict_fit(cars_lm)
#> 316.520309196644 + (disp * 0.246313794518502) + (cyl * -94.5872871981695) +
#> (hp * -2.30500650482876) + (gear * -74.2574697779736) + (disp *
#> cyl * 0.177946383535088) + (disp * hp * 0.00105867448489592) +
#> (cyl * hp * 0.582885559233175) + (disp * gear * -0.0556906400658316) +
#> (cyl * gear * 25.4498752936947) + (hp * gear * 0.565209740210809) +
#> (disp * cyl * hp * -0.00115279922544789) + (disp * cyl *
#> gear * -0.0538061321226812) + (disp * hp * gear * -0.000297318088672666) +
#> (cyl * hp * gear * -0.15344456894624) + (disp * cyl * hp *
#> gear * 0.000329762929171967)
# drop certain items from interactions, tidypredict now erros on the use of :
cars_drop <- step(cars_lm, direction = 'backward', trace = 0)
cars_drop
#>
#> Call:
#> lm(formula = mpg ~ disp + cyl + hp + gear + disp:hp + cyl:hp +
#> disp:gear + cyl:gear + hp:gear + disp:hp:gear + cyl:hp:gear,
#> data = mtcars)
#>
#> Coefficients:
#> (Intercept) disp cyl hp gear
#> 84.708839 1.207121 -52.778801 -0.457745 -8.625052
#> disp:hp cyl:hp disp:gear cyl:gear hp:gear
#> -0.005828 0.277657 -0.333912 13.056098 0.065701
#> disp:hp:gear cyl:hp:gear
#> 0.001572 -0.066664
#but errors here
tidypredict::tidypredict_fit(cars_drop)
#> Error: Functions inside the formula are not supported.
#> - Functions detected: `:`. Use `dplyr` transformations to prepare the data.
sessioninfo::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#> setting value
#> version R version 4.0.0 (2020-04-24)
#> 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 America/Los_Angeles
#> date 2020-06-18
#>
#> ─ Packages ───────────────────────────────────────────────────────────────────
#> package * version date lib source
#> assertthat 0.2.1 2019-03-21 [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)
#> digest 0.6.25 2020-02-23 [1] CRAN (R 4.0.0)
#> dplyr 1.0.0 2020-05-29 [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)
#> generics 0.0.2 2018-11-29 [1] CRAN (R 4.0.0)
#> 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 0.4.0.9003 2020-06-08 [1] Github (rstudio/htmltools@984b39c)
#> knitr 1.28 2020-02-06 [1] CRAN (R 4.0.0)
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#> magrittr 1.5 2014-11-22 [1] CRAN (R 4.0.0)
#> pillar 1.4.4 2020-05-05 [1] CRAN (R 4.0.0)
#> pkgconfig 2.0.3 2019-09-22 [1] CRAN (R 4.0.0)
#> purrr 0.3.4 2020-04-17 [1] CRAN (R 4.0.0)
#> R6 2.4.1 2019-11-12 [1] CRAN (R 4.0.0)
#> rlang 0.4.6 2020-05-02 [1] CRAN (R 4.0.0)
#> rmarkdown 2.2 2020-05-31 [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)
#> tibble 3.0.1 2020-04-20 [1] CRAN (R 4.0.0)
#> tidypredict 0.4.5 2020-02-10 [1] CRAN (R 4.0.0)
#> tidyselect 1.1.0 2020-05-11 [1] CRAN (R 4.0.0)
#> vctrs 0.3.0 2020-05-11 [1] CRAN (R 4.0.0)
#> withr 2.2.0 2020-04-20 [1] CRAN (R 4.0.0)
#> xfun 0.14 2020-05-20 [1] CRAN (R 4.0.0)
#> yaml 2.2.1 2020-02-01 [1] CRAN (R 4.0.0)
#>
#> [1] /Library/Frameworks/R.framework/Versions/4.0/Resources/libraryCreated on 2020-06-18 by the reprex package (v0.3.0)