[R] [effects] allEffects does not accept integer value for xlevels

[Gerrit Eichner]

Dear list,

citing from allEffects' help page (of package effects 4.1-2):
"If xlevels=n is an integer, then each numeric predictor is
represented by n equally spaced values rounded to 'nice' numbers."
	

However, adapting the first example from allEffects' help
page throws an an error:

mod.cowles <- glm(volunteer ~ sex + neuroticism*extraversion,
                   data=Cowles, family=binomial)
allEffects(mod.cowles, xlevels=5)
Error in xlevels[[name]] : subscript out of bounds


It appears to me that the cause is buried in
effects:::Analyze.model

in or close to the the lines

if (is.numeric(xlevels) & length(xlevels) == 1L) {
   levs <- xlevels
   for (name in focal.predictors) xlevels[[name]] <- levs
  }



where xlevels -- while not being a list in this case -- is
subscripted by xlevels[[name]].

Is anyone aware of a workaround (without having to specify all
numeric predictors of the used model explicitly in a list and
giving it to xlevels when calling allEffects), and without
having to write my own Analyze.model function? ;-)


  Thx in advance and best regards  --  Gerrit



PS:  sessionInfo()

R version 3.6.1 (2019-07-05)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 18362)

Matrix products: default

Random number generation:
  RNG:     Mersenne-Twister
  Normal:  Inversion
  Sample:  Rounding

locale:
[1] LC_COLLATE=German_Germany.1252  LC_CTYPE=German_Germany.1252
[3] LC_MONETARY=German_Germany.1252 LC_NUMERIC=C
[5] LC_TIME=German_Germany.1252

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

other attached packages:
[1] effects_4.1-2 carData_3.0-2

loaded via a namespace (and not attached):
  [1] Rcpp_1.0.2        lattice_0.20-38   MASS_7.3-51.4     grid_3.6.1 

  [5] DBI_1.0.0         nlme_3.1-141      survey_3.36 
estimability_1.3
  [9] minqa_1.2.4       nloptr_1.2.1      Matrix_1.2-17     boot_1.3-23 

[13] splines_3.6.1     lme4_1.1-21.9001  survival_2.44-1.1 compiler_3.6.1
[17] colorspace_1.4-1  mitools_2.4       nnet_7.3-12


---------------------------------------------------------------------
Dr. Gerrit Eichner                   Mathematical Institute, Room 212
gerrit.eichner using math.uni-giessen.de   Justus-Liebig-University Giessen
Tel: +49-(0)641-99-32104          Arndtstr. 2, 35392 Giessen, Germany
http://www.uni-giessen.de/eichner