Predict from a workflow

This is the predict() method for a fit workflow object. The nice thing about predicting from a workflow is that it will:

• Preprocess new_data using the preprocessing method specified when the workflow was created and fit. This is accomplished using hardhat::forge(), which will apply any formula preprocessing or call recipes::bake() if a recipe was supplied.

• Call parsnip::predict.model_fit() for you using the underlying fit parsnip model.

# S3 method for workflow
predict(object, new_data, type = NULL, opts = list(), ...)

Arguments

object	A workflow that has been fit by fit.workflow()
new_data	A data frame containing the new predictors to preprocess and predict on
type	A single character value or NULL. Possible values are "numeric", "class", "prob", "conf_int", "pred_int", "quantile", or "raw". When NULL, predict() will choose an appropriate value based on the model's mode.
opts	A list of optional arguments to the underlying predict function that will be used when type = "raw". The list should not include options for the model object or the new data being predicted.
...	Arguments to the underlying model's prediction function cannot be passed here (see opts). There are some parsnip related options that can be passed, depending on the value of type. Possible arguments are: level: for types of "conf_int" and "pred_int" this is the parameter for the tail area of the intervals (e.g. confidence level for confidence intervals). Default value is 0.95. std_error: add the standard error of fit or prediction (on the scale of the linear predictors) for types of "conf_int" and "pred_int". Default value is FALSE. quantile: the quantile(s) for quantile regression (not implemented yet) time: the time(s) for hazard probability estimates (not implemented yet)

Value

A data frame of model predictions, with as many rows as new_data has.

Examples

library(parsnip)
library(recipes)
library(magrittr)

training <- mtcars[1:20,]
testing <- mtcars[21:32,]

model <- linear_reg() %>%
  set_engine("lm")

workflow <- workflow() %>%
  add_model(model)

recipe <- recipe(mpg ~ cyl + disp, training) %>%
  step_log(disp)

workflow <- add_recipe(workflow, recipe)

fit_workflow <- fit(workflow, training)

# This will automatically `bake()` the recipe on `testing`,
# applying the log step to `disp`, and then fit the regression.
predict(fit_workflow, testing)
#> # A tibble: 12 x 1
#>    .pred
#>    <dbl>
#>  1  25.4
#>  2  15.4
#>  3  15.8
#>  4  14.4
#>  5  13.2
#>  6  29.4
#>  7  25.4
#>  8  27.6
#>  9  14.4
#> 10  23.2
#> 11  15.9
#> 12  25.3