use crate::def::grib2::template::param_set::EarthShape;
impl EarthShape {
pub fn radii(&self) -> Option<(f64, f64)> {
let radii = match self.shape {
0 => (6367470.0, 6367470.0),
1 => {
let radius = f64::from(self.spherical_earth_radius_scaled_value)
* f64::powf(10., f64::from(self.spherical_earth_radius_scale_factor));
(radius, radius)
}
2 => (6378160.0, 6356775.0),
3 => {
let (major, minor) = self.radii_defined();
(major * 1000., minor * 1000.)
}
4 => (6378137.0, 6356752.314),
5 => (6378137.0, 6356752.3142), 6 => (6371229.0, 6371229.0),
7 => self.radii_defined(),
8 => (6371200.0, 6371200.0),
9.. => return None,
};
Some(radii)
}
fn radii_defined(&self) -> (f64, f64) {
let major = f64::from(self.major_axis_scaled_value)
* f64::powf(10., f64::from(self.major_axis_scale_factor));
let minor = f64::from(self.minor_axis_scaled_value)
* f64::powf(10., f64::from(self.minor_axis_scale_factor));
(major, minor)
}
}
#[cfg(test)]
mod tests {
use std::{
fs::File,
io::{BufReader, Read},
};
use grib_template_helpers::TryFromSlice;
use super::*;
fn get_uncompressed<P>(file_path: P) -> Result<Vec<u8>, std::io::Error>
where
P: AsRef<std::path::Path>,
{
let mut buf = Vec::new();
let f = File::open(&file_path)?;
let mut f = BufReader::new(f);
match file_path.as_ref().extension().map(|s| s.as_encoded_bytes()) {
Some(b"gz") => {
let mut f = flate2::read::GzDecoder::new(f);
f.read_to_end(&mut buf)?;
}
Some(b"xz") => {
let mut f = xz2::bufread::XzDecoder::new(f);
f.read_to_end(&mut buf)?;
}
_ => {
f.read_to_end(&mut buf)?;
}
};
Ok(buf)
}
#[test]
fn radii_for_shape_1() -> Result<(), Box<dyn std::error::Error>> {
let buf = get_uncompressed("testdata/ds.critfireo.bin.xz")?;
let mut pos = 0x83;
let earth_actual = EarthShape::try_from_slice(&buf, &mut pos)?;
let earth_expected = EarthShape {
shape: 1,
spherical_earth_radius_scale_factor: 0,
spherical_earth_radius_scaled_value: 6371200,
major_axis_scale_factor: 0,
major_axis_scaled_value: 0,
minor_axis_scale_factor: 0,
minor_axis_scaled_value: 0,
};
assert_eq!(earth_actual, earth_expected);
assert_eq!(earth_actual.radii(), Some((6_371_200., 6_371_200.)));
Ok(())
}
#[test]
fn radii_for_shape_2() -> Result<(), Box<dyn std::error::Error>> {
let buf = get_uncompressed(
"testdata/MRMS_ReflectivityAtLowestAltitude_00.50_20230406-120039.grib2.gz",
)?;
let mut pos = 0x33;
let earth_actual = EarthShape::try_from_slice(&buf, &mut pos)?;
let earth_expected = EarthShape {
shape: 2,
spherical_earth_radius_scale_factor: 1,
spherical_earth_radius_scaled_value: 6367470,
major_axis_scale_factor: 1,
major_axis_scaled_value: 6378160,
minor_axis_scale_factor: 1,
minor_axis_scaled_value: 6356775,
};
assert_eq!(earth_actual, earth_expected);
assert_eq!(earth_actual.radii(), Some((6_378_160.0, 6_356_775.0)));
Ok(())
}
#[test]
fn radii_for_shape_4() -> Result<(), Box<dyn std::error::Error>> {
let buf = get_uncompressed(
"testdata/Z__C_RJTD_20160822020000_NOWC_GPV_Ggis10km_Pphw10_FH0000-0100_grib2.bin",
)?;
let mut pos = 0x33;
let earth_actual = EarthShape::try_from_slice(&buf, &mut pos)?;
let earth_expected = EarthShape {
shape: 4,
spherical_earth_radius_scale_factor: 0xff,
spherical_earth_radius_scaled_value: 0xffffffff,
major_axis_scale_factor: 1,
major_axis_scaled_value: 63781370,
minor_axis_scale_factor: 1,
minor_axis_scaled_value: 63567523,
};
assert_eq!(earth_actual, earth_expected);
assert_eq!(earth_actual.radii(), Some((6_378_137.0, 6_356_752.314)));
Ok(())
}
#[test]
fn radii_for_shape_6() -> Result<(), Box<dyn std::error::Error>> {
let buf = get_uncompressed("testdata/gdas.t12z.pgrb2.0p25.f000.0-10.xz")?;
let mut pos = 0x33;
let earth_actual = EarthShape::try_from_slice(&buf, &mut pos)?;
let earth_expected = EarthShape {
shape: 6,
spherical_earth_radius_scale_factor: 0,
spherical_earth_radius_scaled_value: 0,
major_axis_scale_factor: 0,
major_axis_scaled_value: 0,
minor_axis_scale_factor: 0,
minor_axis_scaled_value: 0,
};
assert_eq!(earth_actual, earth_expected);
assert_eq!(earth_actual.radii(), Some((6_371_229.0, 6_371_229.0)));
Ok(())
}
}