A workflow is an object that can bundle together your pre-processing,
modeling, and post-processing requests. For example, if you have a
recipe
and parsnip
model, these can be combined into a workflow. The
advantages are:
You don’t have to keep track of separate objects in your workspace.
The recipe prepping and model fitting can be executed using a single
call to fit()
.
If you have custom tuning parameter settings, these can be defined using a simpler interface when combined with tune.
In the future, workflows will be able to add post-processing operations, such as modifying the probability cutoff for two-class models.
You can install workflows from CRAN with:
install.packages("workflows")
You can install the development version from GitHub with:
# install.packages("devtools")
devtools::install_github("tidymodels/workflows")
Suppose you were modeling data on cars. Say…the fuel efficiency of 32 cars. You know that the relationship between engine displacement and miles-per-gallon is nonlinear, and you would like to model that as a spline before adding it to a Bayesian linear regression model. You might have a recipe to specify the spline:
library(recipes)
library(parsnip)
library(workflows)
spline_cars <- recipe(mpg ~ ., data = mtcars) %>%
step_ns(disp, deg_free = 10)
and a model object:
bayes_lm <- linear_reg() %>%
set_engine("stan")
To use these, you would generally run:
spline_cars_prepped <- prep(spline_cars, mtcars)
bayes_lm_fit <- fit(bayes_lm, mpg ~ ., data = juice(spline_cars_prepped))
You can’t predict on new samples using bayes_lm_fit
without the
prepped version of spline_cars
around. You also might have other
models and recipes in your workspace. This might lead to getting them
mixed-up or forgetting to save the model/recipe pair that you are most
interested in.
workflows makes this easier by combining these objects together:
car_wflow <- workflow() %>%
add_recipe(spline_cars) %>%
add_model(bayes_lm)
Now you can prepare the recipe and estimate the model via a single call
to fit()
:
car_wflow_fit <- fit(car_wflow, data = mtcars)
You can alter existing workflows using update_recipe()
/
update_model()
and remove_recipe()
/ remove_model()
.
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