Apply Target Encoding Map to Frame

Applies a target encoding map to an H2OFrame object. Computing target encoding for high cardinality categorical columns can improve performance of supervised learning models. A Target Encoding tutorial is available here: https://github.com/h2oai/h2o-tutorials/blob/master/best-practices/categorical-predictors/target_encoding.md.

h2o.target_encode_apply(
  data,
  x,
  y,
  target_encode_map,
  holdout_type,
  fold_column = NULL,
  blended_avg = TRUE,
  noise_level = NULL,
  seed = -1
)

Arguments

data

An H2OFrame object with which to apply the target encoding map.

x

A list containing the names or indices of the variables to encode. A target encoding column will be created for each element in the list. Items in the list can be multiple columns. For example, if `x = list(c("A"), c("B", "C"))`, then the resulting frame will have a target encoding column for A and a target encoding column for B & C (in this case, we group by two columns).

y

The name or column index of the response variable in the data. The response variable can be either numeric or binary.

target_encode_map

A list of H2OFrame objects that is the results of the h2o.target_encode_create function.

holdout_type

The holdout type used. Must be one of: "LeaveOneOut", "KFold", "None".

fold_column

(Optional) The name or column index of the fold column in the data. Defaults to NULL (no `fold_column`). Only required if `holdout_type` = "KFold".

blended_avg

Logical. (Optional) Whether to perform blended average.

noise_level

(Optional) The amount of random noise added to the target encoding. This helps prevent overfitting. Defaults to 0.01 * range of y.

seed

(Optional) A random seed used to generate draws from the uniform distribution for random noise. Defaults to -1.

Value

Returns an H2OFrame object containing the target encoding per record.

See also

h2o.target_encode_create for creating the target encoding map

Examples

if (FALSE) { # \dontrun{
library(h2o)
h2o.init()

# Get Target Encoding Frame on bank-additional-full data with numeric `y`
data <- h2o.importFile(
  path = "https://s3.amazonaws.com/h2o-public-test-data/smalldata/demos/bank-additional-full.csv")
splits <- h2o.splitFrame(data, seed = 1234)
train <- splits[[1]]
test <- splits[[2]]
mapping <- h2o.target_encode_create(data = train, x = list(c("job"), c("job", "marital")), 
                                    y = "age")

# Apply mapping to the training dataset
train_encode <- h2o.target_encode_apply(data = train, x = list(c("job"), c("job", "marital")), 
                                        y = "age", mapping, holdout_type = "LeaveOneOut")
# Apply mapping to a test dataset
test_encode <- h2o.target_encode_apply(data = test, x = list(c("job"), c("job", "marital")), 
                                       y = "age", target_encode_map = mapping,
                                       holdout_type = "None")

} # }