# Utilities

## Custom types

Small custom types are used to represent "locations" (2-D) and "positions"
(3-D), some time values and other small enumerations (e.g., aircraft classes).

```{eval-rst}
.. autoclass:: AEIC.types.Location
   :members:
```

```{eval-rst}
.. autoclass:: AEIC.types.Position
   :members:
```

```{eval-rst}
.. autoclass:: AEIC.types.DayOfWeek
   :members:
```

```{eval-rst}
.. autoclass:: AEIC.types.TimeOfDay
   :members:
```

```{eval-rst}
.. autoenum:: AEIC.types.AircraftClass
```

## Airport handling

Airport data is downloaded from the [OurAirports
project](https://ourairports.com/data/). Data for some missing airports is
added from a supplemental CSV file. The canonical way to use this module is as
follows:

```python
from AEIC.utils import airports

...

ap = airports.airport('LHR')
print(f'{ap.name} @ {ap.elevation} MSL')
```

```{eval-rst}
.. automodule:: AEIC.utils.airports
    :members:
    :exclude-members: CountriesData, AirportsData
```

## Unit conversion

Unit conversions are done with simple multiplying factors with a common
`x_TO_y` naming pattern.

```{eval-rst}
.. NOTE::
   The flight level conversions here are based on pressure altitudes, i.e.,
   they simply scale given altitudes by 100 feet intervals.
```

```{eval-rst}
.. automodule:: AEIC.units
    :members:
```

## Geospatial utilities

Great circle distance and azimuth calculations are needed in several places.
These can all be done using the single `pyproj.Geod` instance defined in this
module.

```{eval-rst}
.. autodata:: AEIC.utils.GEOD
```

## File handling functions

```{eval-rst}
.. automodule:: AEIC.utils.files
    :members:
```

## Standard atmosphere

```{eval-rst}
.. automodule:: AEIC.utils.standard_atmosphere
    :members:
```

## Fuel

```{eval-rst}
.. autoclass:: AEIC.types.Fuel
   :members:
```

## Data modeling utility classes

```{eval-rst}
.. automodule:: AEIC.utils.models
    :members:
```