Fine tune a pretrained Transformer model for texts

Fine tune (or train) a pretrained Transformer model for your given training labelled data x and y. The prediction task can be classification (if regression is FALSE, default) or regression (if regression is TRUE).

Usage

grafzahl(
  x,
  y = NULL,
  model_name = "xlm-roberta-base",
  regression = FALSE,
  output_dir,
  cuda = detect_cuda(),
  num_train_epochs = 4,
  train_size = 0.8,
  args = NULL,
  cleanup = TRUE,
  model_type = NULL,
  manual_seed = floor(runif(1, min = 1, max = 721831)),
  verbose = TRUE
)

# Default S3 method
grafzahl(
  x,
  y = NULL,
  model_name = "xlm-roberta-base",
  regression = FALSE,
  output_dir,
  cuda = detect_cuda(),
  num_train_epochs = 4,
  train_size = 0.8,
  args = NULL,
  cleanup = TRUE,
  model_type = NULL,
  manual_seed = floor(runif(1, min = 1, max = 721831)),
  verbose = TRUE
)

# S3 method for class 'corpus'
grafzahl(
  x,
  y = NULL,
  model_name = "xlm-roberta-base",
  regression = FALSE,
  output_dir,
  cuda = detect_cuda(),
  num_train_epochs = 4,
  train_size = 0.8,
  args = NULL,
  cleanup = TRUE,
  model_type = NULL,
  manual_seed = floor(runif(1, min = 1, max = 721831)),
  verbose = TRUE
)

textmodel_transformer(...)

# S3 method for class 'character'
grafzahl(
  x,
  y = NULL,
  model_name = "xlmroberta",
  regression = FALSE,
  output_dir,
  cuda = detect_cuda(),
  num_train_epochs = 4,
  train_size = 0.8,
  args = NULL,
  cleanup = TRUE,
  model_type = NULL,
  manual_seed = floor(runif(1, min = 1, max = 721831)),
  verbose = TRUE
)

Arguments

x: the corpus or character vector of texts on which the model will be trained. Depending on train_size, some texts will be used for cross-validation.
y: training labels. It can either be a single string indicating which docvars of the corpus is the training labels; a vector of training labels in either character or factor; or NULL if the corpus contains exactly one column in docvars and that column is the training labels. If x is a character vector, y must be a vector of the same length.
model_name: string indicates either 1) the model name on Hugging Face website; 2) the local path of the model
regression: logical, if TRUE, the task is regression, classification otherwise.
output_dir: string, location of the output model. If missing, the model will be stored in a temporary directory. Important: Please note that if this directory exists, it will be overwritten.
cuda: logical, whether to use CUDA, default to detect_cuda().
num_train_epochs: numeric, if train_size is not exactly 1.0, the maximum number of epochs to try in the "early stop" regime will be this number times 5 (i.e. 4 * 5 = 20 by default). If train_size is exactly 1.0, the number of epochs is exactly that.
train_size: numeric, proportion of data in x and y to be used actually for training. The rest will be used for cross validation.
args: list, additionally parameters to be used in the underlying simple transformers
cleanup: logical, if TRUE, the runs directory generated will be removed when the training is done
model_type: a string indicating model_type of the input model. If NULL, it will be inferred from model_name. Supported model types are available in supported_model_types.
manual_seed: numeric, random seed
verbose: logical, if TRUE, debug messages will be displayed
...: paramters pass to grafzahl()

Value

a grafzahl S3 object with the following items

call: original function call
input_data: input_data for the underlying python function
output_dir: location of the output model
model_type: model type
model_name: model name
regression: whether or not it is a regression model
levels: factor levels of y
manual_seed: random seed
meta: metadata about the current session

Examples

if (detect_conda() && interactive()) {
library(quanteda)
set.seed(20190721)
## Using the default cross validation method
model1 <- grafzahl(unciviltweets, model_type = "bertweet", model_name = "vinai/bertweet-base")
predict(model1)

## Using LIME
input <- corpus(ecosent, text_field = "headline")
training_corpus <- corpus_subset(input, !gold)
model2 <- grafzahl(x = training_corpus,
                 y = "value",
                 model_name = "GroNLP/bert-base-dutch-cased")
test_corpus <- corpus_subset(input, gold)
predicted_sentiment <- predict(model2, test_corpus)
require(lime)
sentences <- c("Dijsselbloem pessimistisch over snelle stappen Grieken",
               "Aandelenbeurzen zetten koersopmars voort")
explainer <- lime(training_corpus, model2)
explanations <- explain(sentences, explainer, n_labels = 1,
                        n_features = 2)
plot_text_explanations(explanations)
}

Fine tune a pretrained Transformer model for texts

Usage

Arguments

Value

See also

Examples