BCF Serialization Routines

BCF models contains external pointers to C++ objects, which means they cannot be correctly serialized to .Rds from an R session in their default state. These functions allow us to convert between C++ data structures and a persistent JSON representation. The CppJson class wraps a performant C++ JSON API, and the functions saveBCFModelToJson and createBCFModelFromJson save to and load from this format. This representation, of course, also relies on external C++ pointers, so in order to save and reload BCF models across sessions, we provide two other interfaces.

saveBCFModelToJsonFile and createBCFModelFromJsonFile save or reload a BCF model's JSON representation directly to / from a .json file.

saveBCFModelToJsonString and createBCFModelFromJsonString handle in-memory strings containing JSON data, which can be written to disk or passed between processes.

Finally, for cases in which multiple BCF models have been sampled (for instance, sampled in multiple processes via doParallel), we offer createBCFModelFromCombinedJson and createBCFModelFromCombinedJsonString for loading a new combined BCF model from a list of BCF JSON objects or strings.

Usage

saveBCFModelToJson(object)

saveBCFModelToJsonFile(object, filename)

saveBCFModelToJsonString(object)

createBCFModelFromJson(json_object)

createBCFModelFromJsonFile(json_filename)

createBCFModelFromJsonString(json_string)

createBCFModelFromCombinedJson(json_object_list)

createBCFModelFromCombinedJsonString(json_string_list)

Arguments

object

Object of type bcfmodel containing draws of a Bayesian causal forest model and associated sampling outputs.

filename

String of filepath, must end in ".json"

json_object

Object of type CppJson containing Json representation of a BCF model

json_filename

String of filepath, must end in ".json"

json_string

JSON string dump

json_object_list

List of objects of type CppJson containing Json representation of a BCF model

json_string_list

List of JSON strings which can be parsed to objects of type CppJson containing Json representation of a BCF model

Value

saveBCFModelToJson return an object of type CppJson. saveBCFModelToJsonFile returns nothing, but writes to the provided filename. saveBCFModelToJsonString returns a string dump of the BCF model's JSON representation.

createBCFModelFromJson, createBCFModelFromJsonFile, createBCFModelFromJsonString, createBCFModelFromCombinedJson, and createBCFModelFromCombinedJsonString all return objects of type bcfmodel.

Examples

# Generate data
n <- 100
p <- 5
X <- matrix(runif(n*p), ncol = p)
pi_X <- runif(n, 0.3, 0.7)
Z <- rbinom(n, p = pi_X, size = 1)
y <- X[,1] + Z + rnorm(n, 0, 1)

# Sample BCF model
bcf_model <- bcf(X_train = X, Z_train = Z, propensity_train = pi_X, y_train = y,
                 num_gfr = 0, num_burnin = 0, num_mcmc = 10)

# Save to in-memory JSON
bcf_json <- saveBCFModelToJson(bcf_model)
# Save to JSON string
bcf_json_string <- saveBCFModelToJsonString(bcf_model)
# Save to JSON file
tmpjson <- tempfile(fileext = ".json")
saveBCFModelToJsonFile(bcf_model, file.path(tmpjson))

# Reload BCF model from in-memory JSON object
bcf_model_roundtrip <- createBCFModelFromJson(bcf_json)
# Reload BCF model from JSON string
bcf_model_roundtrip <- createBCFModelFromJsonString(bcf_json_string)
# Reload BCF model from JSON file
bcf_model_roundtrip <- createBCFModelFromJsonFile(file.path(tmpjson))
unlink(tmpjson)
# Reload BCF model from list of JSON objects
bcf_model_roundtrip <- createBCFModelFromCombinedJson(list(bcf_json))
# Reload BCF model from list of JSON strings
bcf_model_roundtrip <- createBCFModelFromCombinedJsonString(list(bcf_json_string))