Skip to content

Variable¤

Introducción¤

La aplicación Variable se ocupa de las variables que pueden ser ingeridas por Paricia, desde qué son y qué unidades utilizan hasta recursos para ayudar en el proceso de validación. Especialmente importantes en este proceso de validación serán:

  • los valores máximos y mínimos que la variable puede tomar de forma realista (estos son campos obligatorios)
  • la variabilidad máxima entre puntos de datos consecutivos
  • la diferencia estadística máxima respecto de la serie permitida para un punto de datos antes de que se considere un outlier
  • la fracción de valores faltantes que se permiten al calcular informes

Diagrama UML de los modelos de la aplicación Variable.
Figure 1: Diagrama UML de los modelos de la aplicación Variable.

Componentes¤

Unit ¤

Unit of measurement with a name and a symbol.

Attributes:

Name Type Description
unit_id AutoField

Primary key.
name CharField

Name of the unit, eg. meters per second.
initials CharField

Symbol for the unit, eg. m/s.

Variable ¤

A variable with a physical meaning.

Such as precipitation, wind speed, wind direction, soil moisture, including the associated unit. It also includes metadata to help identify what is a reasonable value for the data, to flag outliers and to help with the validation process.

The nature of the variable can be one of the following:

  • sum: Cumulative value over a period of time.
  • average: Average value over a period of time.
  • value: One-off value.

Attributes:

Name Type Description
variable_id AutoField

Primary key.
variable_code CharField

Code of the variable, eg. airtemperature.
name CharField

Human-readable name of the variable, eg. Air temperature.
unit ForeignKey

Unit of the variable.
maximum DecimalField

Maximum value allowed for the variable.
minimum DecimalField

Minimum value allowed for the variable.
diff_error DecimalField

If two sequential values in the time-series data of this variable differ by more than this value, the validation process can mark this with an error flag.
outlier_limit DecimalField

The statistical deviation for defining outliers, in times the standard deviation (sigma).
null_limit DecimalField

The max % of null values (missing, caused by e.g. equipment malfunction) allowed for hourly, daily, monthly data. Cumulative values are not deemed trustworthy if the number of missing values in a given period is greater than the null_limit.
nature CharField

Nature of the variable, eg. if it represents a one-off value, the average over a period of time or the cumulative value over a period

SensorInstallation ¤

Represents an installation of a Sensor at a Station, which measures a Variable.

It includes metadata for installation and finishing date, as well as state (active or not).

Attributes:

Name Type Description
sensorinstallation_id AutoField

Primary key.
variable ForeignKey

Variable measured by the sensor.
station ForeignKey

Station where the sensor is installed.
sensor ForeignKey

Sensor used for the measurement.
start_date DateField

Start date of the installation.
end_date DateField

End date of the installation.
state BooleanField

Is the sensor active?