Where is this computation running?

Finds a location code for co2int without any network access, in this order:

1. the RMBL_LOCATION environment variable (any code or name the table knows);

2. CODECARBON_COUNTRY_ISO_CODE (alpha-3), the codecarbon variable, so a machine already configured for codecarbon needs nothing more;

3. the system time zone, mapped to its country through the IANA zone tables (America/Toronto is Canada, Europe/Berlin Germany);

4. the territory in the locale (en_CA.UTF-8 is Canada).

When none of these yields a location in the table the answer is "WORLD", and the method says so, so a report never silently applies one country's grid to another's computation.

Usage

dtctloc(
  envloc = Sys.getenv("RMBL_LOCATION"),
  codloc = Sys.getenv("CODECARBON_COUNTRY_ISO_CODE"),
  tz = Sys.timezone(),
  locale = Sys.getlocale("LC_TIME")
)

Arguments

envloc, codloc, tz, locale

The inputs, exposed so a caller or a test can supply them; the defaults read the running session.

Value

A list with location (a code present in co2inttab()) and method (how it was found).

Details

The zone table (inst/extdata/timezone_countries.csv, built by tools/build_timezones.R from the IANA database) holds every zone of zone.tab, which names exactly one country per zone (Europe/Stockholm is Sweden even though the database now keeps its rules under Europe/Berlin), plus the aliases and old names of the backward file under their own country: the country of the zone the alias stood for before the database merged it (Iceland is Atlantic/Reykjavik, Iceland, not Abidjan's Ivory Coast), the link target's country when that target serves a single country (Asia/Calcutta, US/Eastern), and a reviewed list for the rest (Atlantic/Jan_Mayen, America/Coral_Harbour, Canada/Eastern). Every geographic zone OlsonNames() lists resolves to a country or territory; a territory the carbon table has no row of its own for (Monaco, Jersey, Vaduz, the Antarctic stations) uses the grid of the country it draws on or the world average, and the method says which. The Etc/, UTC, fixed-offset and generic zones (CET, EST, WET) name no country and fall through to the locale.

Examples

dtctloc()
#> $location
#> [1] "WORLD"
#> 
#> $method
#> [1] "fallback, no location found in environment, time zone or locale"
#> 
dtctloc(envloc = "", codloc = "", tz = "Europe/Paris")
#> $location
#> [1] "FR"
#> 
#> $method
#> [1] "system time zone Europe/Paris"
#> 
dtctloc(envloc = "", codloc = "", tz = "",
                locale = "en_IN.UTF-8")
#> $location
#> [1] "IN"
#> 
#> $method
#> [1] "locale en_IN.UTF-8"
#> 
# an explicit setting wins over everything else
dtctloc(envloc = "CA-QC", tz = "Europe/Paris")
#> $location
#> [1] "CA-QC"
#> 
#> $method
#> [1] "RMBL_LOCATION environment variable"
#> 
# nothing usable: the world average, and the method says so
dtctloc(envloc = "", codloc = "", tz = "UTC", locale = "C")
#> $location
#> [1] "WORLD"
#> 
#> $method
#> [1] "fallback, no location found in environment, time zone or locale"
#>