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difftimearithmic Transformation

Source: R/difftime.R
step_difftime.Rd

step_difftime() creates a specification of a recipe step that will calculate difftimes of the data.

Usage

step_difftime(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  time = NULL,
  tz = NULL,
  unit = "auto",
  columns = NULL,
  skip = FALSE,
  id = rand_id("difftime")
)

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 which variables are affected by the step. See recipes::selections() for more details. For the tidy method, these are not currently used.

role

Not used by this step since no new variables are created.

trained

A logical to indicate if the quantities for preprocessing have been estimated.

time

date-time or date objects. Used for reference. Must match the type of variable.

tz

an optional time zone specification to be used for the conversion, mainly for "POSIXlt" objects.

unit

character string. Units in which the results are desired. Must be one of "auto", "secs", "mins", "hours","days", and "weeks" Defaults to "auto".

columns

A character string of variable names that will be populated (eventually) by the terms argument.

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 existing steps (if any). For the tidy method, a tibble with columns terms (the columns that will be affected) and base.

Examples

library(recipes)
example_date <- data.frame(
  dates = seq(as.Date("2010/1/1"), as.Date("2016/1/1"), by = "quarter")
 )

 example_datetime <- data.frame(
  datetimes = seq(ISOdate(1993,1,1), ISOdate(1993,1,2), by = "hour")
 )

rec <- recipe(~ dates, data = example_date) %>%
  step_difftime(dates, time = as.Date("2010/1/1"))

difftime_obj <- prep(rec)

bake(difftime_obj, new_data = NULL)
#> # A tibble: 25 × 1
#>       dates
#>       <dbl>
#>  1        0
#>  2  7776000
#>  3 15638400
#>  4 23587200
#>  5 31536000
#>  6 39312000
#>  7 47174400
#>  8 55123200
#>  9 63072000
#> 10 70934400
#> # ℹ 15 more rows

recipe(~ dates, data = example_date) %>%
  step_difftime(dates, time = as.Date("2010/1/1"), unit = "weeks") %>%
  prep() %>%
  bake(new_data = NULL)
#> # A tibble: 25 × 1
#>    dates
#>    <dbl>
#>  1   0  
#>  2  12.9
#>  3  25.9
#>  4  39  
#>  5  52.1
#>  6  65  
#>  7  78  
#>  8  91.1
#>  9 104. 
#> 10 117. 
#> # ℹ 15 more rows

recipe(~ datetimes, data = example_datetime) %>%
  step_difftime(datetimes, time = ISOdate(1993,1,1), unit = "secs") %>%
  prep() %>%
  bake(new_data = NULL)
#> # A tibble: 25 × 1
#>    datetimes
#>        <dbl>
#>  1         0
#>  2      3600
#>  3      7200
#>  4     10800
#>  5     14400
#>  6     18000
#>  7     21600
#>  8     25200
#>  9     28800
#> 10     32400
#> # ℹ 15 more rows