Time feature generator

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.

Value

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

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.

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

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)
#> # A tibble: 3 × 3
#>   terms            value  id        
#>   <chr>            <chr>  <chr>     
#> 1 all_predictors() hour   time_wvoo0
#> 2 all_predictors() minute time_wvoo0
#> 3 all_predictors() second time_wvoo0

time_rec <- prep(time_rec, training = examples)

time_values <- bake(time_rec, new_data = examples)
time_values
#> # A tibble: 5 × 4
#>   times               times_hour times_minute times_second
#>   <dttm>                   <int>        <int>        <dbl>
#> 1 2022-05-07 00:52:08          0           52            8
#> 2 2022-05-07 01:53:09          1           53            9
#> 3 2022-05-07 02:54:10          2           54           10
#> 4 2022-05-07 03:55:11          3           55           11
#> 5 2022-05-07 04:56:12          4           56           12

tidy(time_rec, number = 1)
#> # A tibble: 3 × 3
#>   terms value  id        
#>   <chr> <chr>  <chr>     
#> 1 times hour   time_wvoo0
#> 2 times minute time_wvoo0
#> 3 times second time_wvoo0