Build an explicit Gaussian-process time index — gp_time

Converts numeric, Date, or POSIXt values to elapsed numeric time while retaining origin, unit, and input-class metadata. Input order is never changed: non-increasing time values are rejected.

Usage

gp_time_index(time, unit = "auto")

Arguments

time: Numeric, Date, or POSIXt vector in strictly increasing order.
unit: Time unit for Date or POSIXt inputs. "auto" uses days for Date values, seconds for POSIXt values, and the native scale for numeric inputs.

Value

A numeric vector of elapsed time with class gaussianprocesses_time_index and time metadata in attributes.

Details

Time values are never sorted silently. Non-increasing input is rejected so the temporal order supplied by the user remains explicit.

Stability

Stable: from version 1.0.0 this interface changes incompatibly only in a major release, after a deprecation period. Results and options that concern an experimental model class, kernel, or argument follow that interface's tier. See gaussianprocesses-package for the policy.

Examples

gp_time_index(as.Date("2026-01-01") + c(0, 1, 7))
#> [1] 0 1 7
#> attr(,"origin")
#> [1] "2026-01-01"
#> attr(,"unit")
#> [1] "days"
#> attr(,"input_type")
#> [1] "Date"
#> attr(,"class")
#> [1] "gaussianprocesses_time_index" "numeric"                     

gp_time_index(
  as.POSIXct("2026-01-01 00:00", tz = "UTC") + c(0, 3600, 7200),
  unit = "hours"
)
#> [1] 0 1 2
#> attr(,"origin")
#> [1] "2026-01-01 UTC"
#> attr(,"unit")
#> [1] "hours"
#> attr(,"input_type")
#> [1] "POSIXt"
#> attr(,"class")
#> [1] "gaussianprocesses_time_index" "numeric"