step_time: Time feature generator

In recipes: Preprocessing and Feature Engineering Steps for Modeling

Time feature generator

Description

step_time() creates a specification of a recipe step that will convert date-time data into one or more factor or numeric variables.

Usage

step_time(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  features = c("hour", "minute", "second"),
  columns = NULL,
  keep_original_cols = TRUE,
  skip = FALSE,
  id = rand_id("time")
)

Arguments

recipe	A recipe object. The step will be added to the sequence of operations for this recipe.
...	One or more selector functions to choose variables for this step. The selected variables should have class POSIXct or POSIXlt. See selections() for more details.
role	For model terms created by this step, what analysis role should they be assigned? By default, the new columns created by this step from the original variables will be used as predictors in a model.
trained	A logical to indicate if the quantities for preprocessing have been estimated.
features	A character string that includes at least one of the following values: am (is is AM), hour, hour12, minute, second, decimal_day.
columns	A character string of the selected variable names. This field is a placeholder and will be populated once prep() is used.
keep_original_cols	A logical to keep the original variables in the output. Defaults to TRUE.
skip	A logical. Should the step be skipped when the recipe is baked by bake()? While all operations are baked when prep() is run, some operations may not be able to be conducted on new data (e.g. processing the outcome variable(s)). Care should be taken when using skip = TRUE as it may affect the computations for subsequent operations.
id	A character string that is unique to this step to identify it.

Details

Unlike some other steps, step_time() does not remove the original time variables by default. Set keep_original_cols to FALSE to remove them.

decimal_day return time of day as a decimal number between 0 and 24. for example "07:15:00" would be transformed to 7.25 and "03:59:59" would be transformed to 3.999722. The formula for these calculations are hour(x) + (second(x) + minute(x) * 60) / 3600.

See step_date() if you want to calculate features that are larger than hours.

Value

An updated version of recipe with the new step added to the sequence of any existing operations.

Tidying

When you tidy() this step, a tibble is returned with columns terms, value , and id:

terms

character, the selectors or variables selected

value

character, the feature names

id

character, id of this step

See Also

Other dummy variable and encoding steps: step_bin2factor(), step_count(), step_date(), step_dummy(), step_dummy_extract(), step_dummy_multi_choice(), step_factor2string(), step_holiday(), step_indicate_na(), step_integer(), step_novel(), step_num2factor(), step_ordinalscore(), step_other(), step_regex(), step_relevel(), step_string2factor(), step_unknown(), step_unorder()

Examples

library(lubridate)

examples <- data.frame(
  times = ymd_hms("2022-05-06 23:51:07") +
  hours(1:5) + minutes(1:5) + seconds(1:5)
)
time_rec <- recipe(~ times, examples) %>%
  step_time(all_predictors())

tidy(time_rec, number = 1)

time_rec <- prep(time_rec, training = examples)

time_values <- bake(time_rec, new_data = examples)
time_values

tidy(time_rec, number = 1)

recipes documentation built on July 4, 2024, 9:06 a.m.