locally defined imputation method does not work with futuremice

[HJardel]

I have code using mice that works fine but takes a long time. It uses a custom function as a default (called mice.impute.logreg_2). When I try to use futuremice (just changing "mice" from "futuremice"), I get an error:
Error in get(fn) : object 'mice.impute.logreg_2' not found.
My best guess is this is has to do with how the futures package is called and needing to specify it as an additional global. I figured it might be worth a patch to make futuremice as interchangeable with mice as possible.

[thomvolker]

As a quick fix, you can clone the mice package from GitHub, add your function as an imputation function and rebuild the package. In this way, I presume that futuremice will locate your function, which then means that you can proceed.

I will dive in the issue, but don't have time to do so right now.

[stefvanbuuren]

Tom, thanks. I understand #550 has solved the problem, so I'm closing.

[oloverm]

For reference, the solution is to pass in any locally defined functions, as well as objects (such as the predictor matrix or vector of methods), to globals. For example:

imputed <- mice::futuremice(
  to_impute, 
  predictorMatrix = imputation_predictor_matrix,
  method = imputation_methods,
  globals = c("imd_score_to_quintile", "imputation_predictor_matrix", "imputation_methods")
)