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holidays

Deciding which holidays do apply

Because each country/culture has it‘s own important dates/events, holidays are defined on a country level. The country wide definition can be overwritten as needed by more specific definitions. Because this library works with the OSM ecosystem, those boundaries are based on OSM.

More specifically, the dataset on which a decision is made which holidays apply for a given location is based on Nominatim.

Consider this Nominatim reverse geocoding query: https://nominatim.openstreetmap.org/reverse?format=json&lat=49.5487&lon=9.8160&zoom=18&addressdetails=1&accept-language=de,en

which returned the following JSON object:

{
  "place_id": "2614369044",
  "licence": "Data © OpenStreetMap contributors, ODbL 1.0. https://www.openstreetmap.org/copyright",
  "osm_type": "way",
  "osm_id": "416578669",
  "lat": "49.5438327",
  "lon": "9.8155867",
  "display_name": "K 2847, Lauda-Königshofen, Main-Tauber-Kreis, Regierungsbezirk Stuttgart, Baden-Württemberg, 97922, Deutschland",
  "address": {
    "road": "K 2847",
    "town": "Lauda-Königshofen",
    "county": "Main-Tauber-Kreis",
    "state_district": "Regierungsbezirk Stuttgart",
    "state": "Baden-Württemberg",
    "postcode": "97922",
    "country": "Deutschland",
    "country_code": "de"
  },
  "boundingbox": [
    "49.5401338",
    "49.5523393",
    "9.8003394",
    "9.8274515"
  ]
}

as of 2016-06-29.

For now it has been enough to make a decision based on the fields address.country_code and address.state and thus only those two levels are supported right now in the data format. But the other information is there when needed, just extend the data format and source code to make use of it.

Note that you will need to use exactly the same values that Nominatim returns in the holiday definition data format which is described next. Also note that the definition is based on Nominatim results in local language so you will likely need to adjust the accept-language URL get parameter from the example. Refer to Nominatim/Country Codes for the country codes to language code mapping used for this specification.

You can use https://www.openstreetmap.org to get the coordinates for the states you are defining holidays for. Just search the state and position the map view on that state. Copy the latitude and longitude from the address bar. Consider this example of a permalink:

https://www.openstreetmap.org/#map=15/49.5487/9.8160

You can now use the &lat=49.5487&lon=9.8160 parameters and use them instead of the once in the example Nominatim query shown above. Note that you should include this Nominatim URL for each defined state using the _nominatim_url key (see below). The _nominatim_url is intended to make testing of the holiday definitions easier.

You could also do a Nominatim search directly using: https://nominatim.openstreetmap.org/search?format=json&country=Deutschland&state=Berlin&&zoom=18&addressdetails=1&limit=1&accept-language=de,en and then do the Nominatim reverse geocoding using the returned coordinates. But note that the _nominatim_url needs to be a Nominatim reverse geocoding query because of different attributes being returned.

Holiday definition format

Data format version 2.2.0. The data format will probably need to be adapted to support more holiday definitions in the future. The data format versioning complies with Semantic Versioning.

Each country has it’s own YAML file below ./holidays/ with the address.country_code as the file name. Lets take a look at the (shortened) de.yaml file as an example for the general structure:

---

_nominatim_url: 'https://nominatim.openstreetmap.org/reverse?format=json&lat=49.5487&lon=9.8160&zoom=18&addressdetails=1&accept-language=de,en'
# Somewhere in this country.

PH: {}  # https://de.wikipedia.org/wiki/Feiertage_in_Deutschland

Baden-Württemberg:  # Does only apply in Baden-Württemberg
  _state_code: bw
  # Short string which can be used to refer to this entry in the test framework.
  # Needs to be unique for the country wide definition.
  # Should be specified when a commonly known code exists for the country/state.

  _nominatim_url: 'https://nominatim.openstreetmap.org/reverse?format=json&lat=49.5487&lon=9.8160&zoom=18&addressdetails=1&accept-language=de,en'
  # Somewhere in this state/state.

  # PH: {}
  # This more specific rule set overwrites the country wide one (they are just ignored).
  # You may use this instead of the country wide with when one state
  # totally disagrees about how to do public holidays.

  SH: []
  # school holiday normally variate between states

The dictionary of the country either consists of PH, SH or the value of address.state (under the assumption that address.state will never be equal to PH or SH, probably a poor assumption, will need to be changed). When PH or SH is defined at this level it applies country wide. Those country wide definitions can be overwritten for an address.state by creating an additional dictionary with the name set to address.state and define PH or SH accordingly.

Note that the data format versions below 2.2.0 used JSON as data serialization language. The data structure remains the same as 2.1.0 however.

Holiday definition format: PH

Now lets look at the public holiday (PH) definition in more detail. Each PH definition consists of a dictionary with holiday name as key and date definition as values (specifying one day). Holiday names should be in the local language. A date definition either consists of two integers representing month and day or the name of a movable event and the offset to that event. The movable events and the formulas for calculating them for a given year are defined in the getMovableEventsForYear function.

PH:  # https://de.wikipedia.org/wiki/Feiertage_in_Deutschland
  'Neujahrstag': [1, 1]
  'Heilige Drei Könige': [1, 6, [Baden-Württemberg, Bayern, Sachsen-Anhalt]]
  'Tag der Arbeit': [5, 1]
  'Karfreitag': [easter, -2]
  'Ostersonntag': [easter, 0, [Brandenburg]]
  'Ostermontag': [easter, 1]
  'Christi Himmelfahrt': [easter, 39]
  'Pfingstsonntag': [easter, 49, [Brandenburg]]
  'Pfingstmontag': [easter, 50]
  'Fronleichnam': [easter, 60, [Baden-Württemberg, Bayern, Hessen, Nordrhein-Westfalen, Rheinland-Pfalz, Saarland]]
  'Mariä Himmelfahrt': [8, 15, [Saarland]]
  'Tag der Deutschen Einheit': [10, 3]
  'Reformationstag': [10, 31, [Brandenburg, Mecklenburg-Vorpommern, Sachsen, Sachsen-Anhalt, Thüringen]]
  'Allerheiligen': [11, 1, [Baden-Württemberg, Bayern, Nordrhein-Westfalen, Rheinland-Pfalz, Saarland]]
  'Buß- und Bettag': [nextWednesday16Nov, 0, [Sachsen]]
  '1. Weihnachtstag': [12, 25]
  '2. Weihnachtstag': [12, 26]

Note that the array of date definitions can hold an optional array of address.state strings. When this list is present, the holiday is only applied when address.state is found in that array of strings.

Holiday definition format: SH

School holiday (SH) definitions look a little bit different. This is because school holidays usually spans multiple days and because SH are different for each year/can not be mathematically calculated (at least the countries that @ypid has seen so far). This is not very nice, but as we are hackers, we can just grab the data and convert it into the data format documented here. This is what @ypid has been doing for all states in Germany using the hc tool which was developed for use with this library and which fellows might find useful to convert holidays for other countries as well.

Now to the data format. It consists of an array of dictionaries. Each dictionary defines one school holiday. The name key defines the name of the school holiday, again preferably in local language. 4-digit string keys define the year with a time range definition as value. The time range definition is an array consisting of a multiple of 4 integers.

Meaning of the integers:

1 and 2: Month and day of the first day of the school holiday.

3 and 4: Month and day of the last day of the school holiday.

Multiple time ranges can be defined.

# Everything below is generated and kept up-to-date by hc.
SH:
  - name: Osterferien
    '2017': [4, 10, 4, 21]
    '2018': [3, 26, 4, 6]
  - name: Pfingstferien
    '2017': [6, 6, 6, 16]
    '2018': [5, 22, 6, 2]
  - name: Sommerferien
    '2017': [7, 27, 9, 9]
    '2018': [7, 26, 9, 8]
  - name: Herbstferien
    '2017': [10, 30, 11, 3]
    '2018': [10, 29, 11, 2]
  - name: Weihnachtsferien
    '2017': [12, 22, 1, 5]
    '2018': [12, 24, 1, 5]

Note that the 4-digit keys define the year are in fact strings. This is done for compatibility reasons.

Also note that past year definitions can be removed from the definition as long as the SH dataset can be regenerated as a whole by Free Software without depending on none-cached resources and as long as the unit tests pass which might where written against previous holidays. Two years in the past should be more then enough for the typical use cases of the library. In the far future, a compile time option might be provided to make this configurable to also make historian’s happy.

Hints

  • Note that you should include the definitions in order (see #126 for details).
  • Please also add the source for this information (in form of an URL) as comment. Like shown in the examples above. Usually Wikipedia in the local language is a great source.