Source code for satpy.tests.reader_tests.test_viirs_vgac_l1c_nc

#!/usr/bin/env python
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"""The viirs_vgac_l1b_nc reader tests package.

This version tests the readers for VIIIRS VGAC data preliminary version.

"""


import datetime as dt

import numpy as np
import pytest
import xarray as xr
from netCDF4 import Dataset


[docs] @pytest.fixture() def nc_filename(tmp_path): """Create an nc test data file and return its filename.""" now = dt.datetime.utcnow() filename = f"VGAC_VJ10XMOD_A{now:%Y%j_%H%M}_n004946_K005.nc" filename_str = str(tmp_path / filename) # Create test data with Dataset(filename_str, "w") as nc: nscn = 7 npix = 800 n_lut = 12000 start_time_srting = "2023-03-28T09:08:07" end_time_string = "2023-03-28T10:11:12" nc.createDimension("npix", npix) nc.createDimension("nscn", nscn) nc.createDimension("n_lut", n_lut) nc.createDimension("one", 1) nc.StartTime = start_time_srting nc.EndTime = end_time_string for ind in range(1, 11, 1): ch_name = "M{:02d}".format(ind) r_a = nc.createVariable(ch_name, np.int16, dimensions=("nscn", "npix")) r_a[:] = np.ones((nscn, npix)) * 10 attrs = {"scale_factor": 0.1, "units": "percent"} for attr in attrs: setattr(r_a, attr, attrs[attr]) for ind in range(12, 17, 1): ch_name = "M{:02d}".format(ind) tb_b = nc.createVariable(ch_name, np.int16, dimensions=("nscn", "npix")) tb_b[:] = np.ones((nscn, npix)) * 800 attrs = {"units": "radiances", "scale_factor": 0.002} for attr in attrs: setattr(tb_b, attr, attrs[attr]) tb_lut = nc.createVariable(ch_name + "_LUT", np.float32, dimensions=("n_lut")) tb_lut[:] = np.array(range(0, n_lut)) * 0.5 tb_lut.units = "Kelvin" reference_time = np.datetime64("2010-01-01T00:00:00") start_time = np.datetime64("2023-03-28T09:08:07") + np.timedelta64(123000, "us") delta_days = start_time - reference_time delta_full_days = delta_days.astype("timedelta64[D]") hidden_reference_time = reference_time + delta_full_days delta_part_of_days = start_time - hidden_reference_time proj_time0 = nc.createVariable("proj_time0", np.float64) proj_time0[:] = (delta_full_days.astype(np.int64) + 0.000001 * delta_part_of_days.astype("timedelta64[us]").astype(np.int64) / (60 * 60 * 24)) proj_time0.units = "days since 01/01/2010T00:00:00" time_v = nc.createVariable("time", np.float64, ("nscn",)) delta_h = np.datetime64(end_time_string) - start_time delta_hours = 0.000001 * delta_h.astype("timedelta64[us]").astype(np.int64) / (60 * 60) time_v[:] = np.linspace(0, delta_hours, num=nscn).astype(np.float64) time_v.units = "hours since proj_time0" return filename_str
[docs] class TestVGACREader: """Test the VGACFileHandler reader."""
[docs] def test_read_vgac(self, nc_filename): """Test reading reflectances and BT.""" from satpy.scene import Scene # Read data scn_ = Scene( reader="viirs_vgac_l1c_nc", filenames=[nc_filename]) scn_.load(["M05", "M15", "scanline_timestamps"]) diff_s = (scn_["scanline_timestamps"][0].values.astype("datetime64[us]") - np.datetime64("2023-03-28T09:08:07.123000").astype("datetime64[us]")) diff_e = (np.datetime64("2023-03-28T10:11:12.000000").astype("datetime64[us]") - scn_["scanline_timestamps"][-1].values.astype("datetime64[us]")) assert (diff_s < np.timedelta64(5, "us")) assert (diff_s > np.timedelta64(-5, "us")) assert (diff_e < np.timedelta64(5, "us")) assert (diff_e > np.timedelta64(-5, "us")) assert (scn_["M05"][0, 0] == 100) assert (scn_["M15"][0, 0] == 400) assert scn_.start_time == dt.datetime(year=2023, month=3, day=28, hour=9, minute=8, second=7) assert scn_.end_time == dt.datetime(year=2023, month=3, day=28, hour=10, minute=11, second=12)
[docs] def test_dt64_to_datetime(self): """Test datetime conversion branch.""" from satpy.readers.viirs_vgac_l1c_nc import VGACFileHandler fh = VGACFileHandler(filename="", filename_info={"start_time": "2023-03-28T09:08:07"}, filetype_info="") in_dt = dt.datetime(year=2023, month=3, day=28, hour=9, minute=8, second=7) out_dt = fh.dt64_to_datetime(in_dt) assert out_dt == in_dt
[docs] def test_decode_time_variable(self): """Test decode time variable branch.""" from satpy.readers.viirs_vgac_l1c_nc import VGACFileHandler fh = VGACFileHandler(filename="", filename_info={"start_time": "2023-03-28T09:08:07"}, filetype_info="") data = xr.DataArray( [[1, 2], [3, 4]], dims=("y", "x"), attrs={"units": "something not expected"}) with pytest.raises(AttributeError): fh.decode_time_variable(data, "time", None)