weather-type

A library for parsing weather type strings.

Why

Various weather APIs provide some form of 'weather type' description, eg 'clear' or 'light rain'. This library parses these into objects that can be compared and combined, for example to enable averaging multiple weather types. It also converts these descriptions to a small set of description codes.

Install

npm install weather-type

Example

var WeatherType = require('weather-type');

WeatherType.default.fromString('Drizzle').map(weatherType => {
  weatherType.clouds.level === WeatherType.CloudLevel.Light; // true
  weatherType.clouds.level === WeatherType.CloudLevel.Heavy; // false

  weatherType.storm.level === WeatherType.StormLevel.None; // true

  weatherType.precipitation.level === WeatherType.PrecipitationLevel.Light; // true
  weatherType.precipitation.duration === WeatherType.PrecipitationDuration.Showers; // true
  weatherType.precipitation.type === WeatherType.PrecipitationType.Rain; // true

  weatherType.toCode(); // 'light_rain_showers'
});

Design

This models weather types as a combination of several factors:

• Storm level
• Cloud level
• Precipitation level
• Precipitation type
• Precipitation duration

These each have a set of possible numeric values corresponding to a string description. Any numeric value can be substituted for a value in a particular WeatherType instance and, when the description code is generated, the closest value in the range of possible values will be used. This makes it possible to find an average WeatherType over a set of WeatherTypes by creating a WeatherType with the average component values of the set of WeatherTypes.

Usage

WeatherType.fromString(code: string): Option<WeatherType>

Not all strings are parseable into WeatherTypes, so this returns an Option (using option-t).

new WeatherType(storm: Storm, precipitation: Precipitation, clouds: Clouds)

Constructs a WeatherType instance from its components (see below).

WeatherType#toCode(): string

Returns the description code that best describes this WeatherType instance, based on its storm, precipitation and clouds components.

new Clouds(level: number)

Possible values of level:

• 0 (corresponds to 'clear')
• 1 (corresponds to 'broken_clouds')
• 2 (corresponds to 'light_clouds')
• 3 (corresponds to 'heavy_clouds')
• 4 (corresponds to 'mist')
• 5 (corresponds to 'fog')

Each of these values has an associated boolean reader, eg isClear(), for convenience, which returns true if level rounds to the corresponding value.

new Precipitation(level: number, duration: number, type: number)

Possible values of level:

• 0 (corresponds to 'none')
• 1 (corresponds to 'light')
• 2 (corresponds to 'heavy')

Possible values of duration:

• 0 (corresponds to 'showers')
• 1 (corresponds to 'steady')

Possible values of type:

• 0 (corresponds to 'rain')
• 1 (corresponds to 'sleet')
• 2 (corresponds to 'snow')
• 2 (corresponds to 'hail')

Each of these values, apart from none, has an associated boolean reader, eg isLight(), for convenience. They return true if the appropriate variable corresponds to the specified value.

Precipitation#isApplicable(): boolean

Returns true if level rounds to a value greater that 0.

new Storm(level: number)

Possible values of level:

• 0 (corresponds to 'none')
• 1 (corresponds to 'thunderstorm')

Storm#isApplicable(): boolean

Returns true if level rounds to a value greater that 0.

Description codes

The full list of description codes that the library can output are (in rough order of precedence):

• thunderstorm
• heavy_hail
• heavy_snow
• heavy_sleet
• heavy_rain
• heavy_hail_showers
• heavy_snow_showers
• heavy_sleet_showers
• heavy_rain_showers
• light_hail
• light_snow
• light_sleet
• light_rain
• light_hail_showers
• light_snow_showers
• light_sleet_showers
• light_rain_showers
• Fog
• Mist
• heavy_clouds
• light_clouds
• broken_clouds
• clear

Tests

The tests are not distributed with the npm package (to reduce its size). To run the tests, please clone this repo from github, then run the tests:

git clone https://github.com/dp28/weather-type.git
cd weather-type
npm install
karma start

License

MIT