twilight_create: Estimate twilights from light data

In Rafnuss/GeoPressureR: Global Positioning by Atmospheric Pressure

Estimate twilights from light data

Description

This function estimate twilight (i.e., datetime of sunrise and sunset) by searching for the first and last light of the day which is defined by the light exceeds or falls below the light threshold twl_thr.

Usage

twilight_create(tag, twl_thr = NULL, twl_offset = NULL, transform_light = TRUE)

Arguments

tag	a GeoPressureR tag object
twl_thr	Light threshold that defines twilight. By default (NULL), it uses the smallest value of light (i.e, first and last light of day).
twl_offset	Shift of the middle of the night compared to 00:00 UTC (in hours). If not provided, it uses the middle of all nights.
transform_light	logical to use a log transformation of light

Value

a tag list containing a new data.frame twilight with columns:

• twilight (date-time of twilight)

• rise (logical) indicating sunrise (TRUE) or sunset (FALSE).

• stap_id if stap_id is present in light.

See Also

GeoPressureManual , TwGeos::findTwilights()

Other geolight: geolight_map(), twilight_label_read(), twilight_label_write()

Examples

withr::with_dir(system.file("extdata", package = "GeoPressureR"), {
  tag <- tag_create("18LX", quiet = TRUE) |> tag_label(quiet = TRUE)
})

# Create twilight data.frame
tag <- twilight_create(tag)

str(tag$twilight)

plot(tag, type = "twilight")

Rafnuss/GeoPressureR documentation built on April 17, 2025, 12:58 p.m.