get predictor data types from H2OModel

问题

I know that I can access the predictor names of an H2OModel via the @parameters slot, but can I access the predictor data types?

I'm trying to generate an input schema for my h2OModel, and right now I have to cross-reference the training_frame and get data types from there. Obviously, this would be a problem if my training_frame was no longer in memory.

Here's my current approach:

getInputSchema <- function(model){
  require(jsonlite)
  require(h2o)
  training_frame <- h2o.getFrame(model@parameters$training_frame)
  toJSON(
      setNames( h2o.getTypes(training_frame), 
                names(training_frame)        
               )[model@parameters$x], 
      auto_unbox = T 
      )
}

and an example of how it could be used:

#--- Example dataset ----
library(h2o)
library(data.table)
options('h2o.use.data.table'=TRUE)
library(rpart.plot) # for 'ptitanic' dataset
h2o.init()
data(ptitanic, package='rpart.plot')
survival <- as.h2o(
              setDT( ptitanic)[, `:=`( age   = as.numeric(age),
                                       sibsp = as.integer(sibsp),
                                       parch = as.integer(parch)
                                     ) ] 
            )
#--- Example model -----
fit <- 
  h2o.gbm( x = c('pclass','sex','age','sibsp','parch'),
           y = 'survived',
           training_frame = survival
          )
#--- Example use ----
getInputSchema(fit)
# {"pclass":"enum","sex":"enum","age":"real","sibsp":"int","parch":"int"}

I'm looking for a solution that I could apply to an existing model where the dataset referenced in training_frame is missing.

来源：https://stackoverflow.com/questions/52431210/get-predictor-data-types-from-h2omodel