A Kotlin library and associated applications for analysing weather station data read from a CSV file - see data/README.md for details of the format.

Note: LICENSE applies to the Kotlin code. The CSV files in the data directory are covered by the Open Government License.

This consists of three classes: WeatherFile, WeatherRecord and WeatherDataset. You can run the tests for these classes with

./gradlew :lib:test

WeatherFile represents a CSV file containing weather station data. It does some basic checking that the file exists and that it has a valid header when you attempt to read from it. Calling the lines() method will return a sequence of lines from the file but this class does no further processing of the data, leaving that task to WeatherDataset.

A WeatherRecord object captures a subset of the data in one record from the CSV file, specifically: date & time, wind speed (metres per second), temperature (Celsius), solar irradiance (Watts per square metre), and relative humidity (%). All of the meteorological measurements are nullable, nulls being used to indicate a particular measurement is unavailable for the date & time in question.

A WeatherDataset object encapsulates a sequence of WeatherRecord objects created from data in a CSV file. The file is specified as a WeatherFile object. This object's lines() method will be invoked by WeatherDataset in order to read the data.

val file = WeatherFile("weather.csv")
val dataset = WeatherDataset(file)

When processing the data read from the file, records with the wrong number of fields, or a missing date & time field, or a badly formatted date & time field, will be skipped.

Once you have created a dataset, you can access the size and skipped properties to see how many records from the CSV file were stored and how many were ignored. You can also see how many of the meteorological measurements are missing by accessing the properties missingWindSpeed, missingTemperature, missingIrradiance and missingHumidity.

You can access records individually by their position, or iterate over the entire dataset:

val firstRecord = dataset[0]

for (record in dataset) {
    println(record.temperature ?: "?")
}

The following analysis methods are provided:

• maxWindSpeed(), to find the record having the highest wind speed
• minTemperature(), to find the record having the lowest temperature
• maxTemperature(), to find the record having the highest temperature
• minHumidity(), to find the record having the lowest humidity
• maxHumidity(), to find the record having thr highest humidity

Each of these can return null in the case of an empty dataset or a dataset in which measurements are not available for the meteorological parameter of interest.

In addition, the insolation over a 24-hour period at the measurement site can be computed:

val date = LocalDate.of(2019, 3, 8)
dataset.insolation(date)?.let {
    println("Insolation on $date = ${it.first} J/m2")
    println("Computed over ${it.second} hours of measurements")
}

Note that the insolation method returns null if no records are available for the given date, otherwise it returns a Pair containing the computed insolation and the number of hours over which solar irradiance was integrated. Pair(0.0, 0) will be returned if the date is valid but no measurements of irradiance were acquired on that date for some reason.

This application takes the path to a CSV file of weather data as its sole command line argument.

It reports on

• Numbers of processed and skipped records
• How many missing measurements there were in the dataset
• Maximum wind speed, and the time on which this was measured
• Minimum & maximum temperature, and the times on which these were measured
• Minimum & maximum humidity, and the times on which these were measured

You can try out the application with Gradle using

./gradlew :stats:run

Use --args to override the hard-coded input filename, e.g.,

./gradlew :stats:run --args="../data/leeds_2011-2018.csv"

You can package the application for distribution like so:

./gradlew :stats:distZip

This application takes the path to a CSV file of weather data and a date as command line arguments. The date should be formatted according to ISO 8601, i.e., YYYY-MM-DD.

The application computes insolation on the specified date by integrating solar irradiance measurements over that date. It displays both the computed value and the number of hours over which it was computed.

You can try out the application with Gradle using

./gradlew :insolation:run

You can specify your own command line arguments using the --args option:

./gradlew :insolation:run --args="../data/leeds_2019.csv 2019-04-19"

You can package the application for distribution like so:

./gradlew :insolation:distZip