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Fix LightningTimeCompositor failing when data outside of the time range is passed #3057

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Fix LightningTimeCompositor failing when data outside of the time range is passed #3057

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dfd7eea
remove drop=True and raise only a warning, fix language
ameraner Feb 11, 2025
6a4ca86
update tests
ameraner Feb 11, 2025
f461e5b
fix typo and reformat
ameraner Feb 11, 2025
e6b5385
fix typo
ameraner Feb 11, 2025
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32 changes: 15 additions & 17 deletions satpy/composites/lightning.py
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Original file line number Diff line number Diff line change
Expand Up @@ -28,11 +28,11 @@


class LightningTimeCompositor(CompositeBase):
"""Class used to create the flash_age compositor usefull for lighting event visualisation.
"""Compositor class for lightning visualisation based on time.

The datas used are dates related to the lightning event that should be normalised between
0 and 1. The value 1 corresponds to the latest lightning event and the value 0 corresponds
to the latest lightning event - time_range. The time_range is defined in the satpy/etc/composites/li.yaml
The compositor normalises the lightning event times between 0 and 1.
The value 1 corresponds to the latest lightning event and the value 0 corresponds
to the latest lightning event - time_range. The time_range is defined in the composite recipe
and is in minutes.
"""
def __init__(self, name, prerequisites=None, optional_prerequisites=None, **kwargs):
Expand All @@ -49,7 +49,8 @@ def _normalize_time(self, data:xr.DataArray, attrs:dict) -> xr.DataArray:

The range of the normalised data is between 0 and 1 where 0 corresponds to the date end_time - time_range
and 1 to the end_time. Where end_times represent the latest lightning event and time_range is the range of
time you want to see the event.The dates that are earlier to end_time - time_range are removed.
time in minutes visualised in the composite.
The dates that are earlier to end_time - time_range are set to NaN.

Args:
data (xr.DataArray): datas containing dates to be normalised
Expand All @@ -62,16 +63,14 @@ def _normalize_time(self, data:xr.DataArray, attrs:dict) -> xr.DataArray:
end_time = np.array(np.datetime64(data.attrs[self.reference_time_attr]))
# Compute the minimum time value based on the time range
begin_time = end_time - np.timedelta64(self.time_range, "m")
# Drop values that are bellow begin_time
# Invalidate values that are before begin_time
condition_time = data >= begin_time
condition_time_computed = condition_time.compute()
data = data.where(condition_time_computed, drop=True)
# exit if data is empty afer filtering
if data.size == 0 :
LOG.error(f"All the flash_age events happened before {begin_time}")
raise ValueError(f"Invalid data: data size is zero. All flash_age "
f"events occurred before the specified start time ({begin_time})."
)
data = data.where(condition_time)

# raise a warning if data is empty after filtering
if np.all(np.isnan(data)) :
LOG.warning(f"All the flash_age events happened before {begin_time}, the composite will be empty.")

# Normalize the time values
normalized_data = (data - begin_time) / (end_time - begin_time)
# Ensure the result is still an xarray.DataArray
Expand All @@ -91,15 +90,14 @@ def _redefine_metadata(self,attrs:dict)->dict:
attrs (dict): data's attributes

Returns:
dict: atualised attributes
dict: updated attributes
"""
attrs["name"] = self.standard_name
attrs["standard_name"] = self.standard_name
# Attributes to describe the values range
return attrs


def __call__(self,projectables, nonprojectables=None, **attrs):
def __call__(self, projectables, nonprojectables=None, **attrs):
"""Normalise the dates."""
data = projectables[0]
new_attrs = data.attrs.copy()
Expand Down
57 changes: 25 additions & 32 deletions satpy/tests/compositor_tests/test_lightning.py
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,6 @@

import dask.array as da
import numpy as np
import pytest
import xarray as xr

from satpy.composites.lightning import LightningTimeCompositor
Expand All @@ -32,7 +31,7 @@
def test_flash_age_compositor():
"""Test the flash_age compsitor by comparing two xarrays object."""
comp = LightningTimeCompositor("flash_age",prerequisites=["flash_time"],
standard_name="ligtning_time",
standard_name="lightning_time",
time_range=60,
reference_time="end_time")
attrs_flash_age = {"variable_name": "flash_time","name": "flash_time",
Expand All @@ -41,53 +40,47 @@ def test_flash_age_compositor():
flash_age_value = da.array(["2024-08-01T09:00:00",
"2024-08-01T10:00:00", "2024-08-01T10:30:00","2024-08-01T11:00:00"], dtype="datetime64[ns]")
flash_age = xr.DataArray(
flash_age_value,
dims=["y"],
coords={
"crs": "8B +proj=longlat +ellps=WGS84 +type=crs"
},attrs = attrs_flash_age,name="flash_time")
flash_age_value,
dims=["y"],
coords={
"crs": "8B +proj=longlat +ellps=WGS84 +type=crs"},
attrs = attrs_flash_age,
name="flash_time")
res = comp([flash_age])
expected_attrs = {"variable_name": "flash_time","name": "lightning_time",
"start_time": datetime.datetime(2024, 8, 1, 10, 50, 0),
"end_time": datetime.datetime(2024, 8, 1, 11, 0, 0),"reader": "li_l2_nc",
"standard_name": "ligtning_time"
"standard_name": "lightning_time"
}
expected_array = xr.DataArray(
da.array([0.0,0.5,1.0]),
dims=["y"],
coords={
"crs": "8B +proj=longlat +ellps=WGS84 +type=crs"
},attrs = expected_attrs,name="flash_time")
expected_array = xr.DataArray(da.array([np.nan, 0.0,0.5,1.0]),
dims=["y"],
coords={
"crs": "8B +proj=longlat +ellps=WGS84 +type=crs"},
attrs = expected_attrs,
name="flash_time")
xr.testing.assert_equal(res,expected_array)

def test_empty_array_error(caplog):
"""Test when the filtered array is empty."""
comp = LightningTimeCompositor("flash_age",prerequisites=["flash_time"],
standard_name="ligtning_time",
standard_name="lightning_time",
time_range=60,
reference_time="end_time")
attrs_flash_age = {"variable_name": "flash_time","name": "flash_time",
"start_time": np.datetime64(datetime.datetime(2024, 8, 1, 10, 0, 0)),
"end_time": datetime.datetime(2024, 8, 1, 11, 0, 0),
"reader": "li_l2_nc"}
flash_age_value = da.array(["2024-08-01T09:00:00"], dtype="datetime64[ns]")
flash_age = xr.DataArray(
flash_age_value,
dims=["y"],
coords={
"crs": "8B +proj=longlat +ellps=WGS84 +type=crs"
},attrs = attrs_flash_age,name="flash_time")
with caplog.at_level(logging.ERROR):
# Simulate the operation that raises the exception
with pytest.raises(ValueError, match="data size is zero") as excinfo:
_ = comp([flash_age])

# Assert the exception message
assert str(excinfo.value) == (
f"Invalid data: data size is zero. All flash_age events occurred before "
f"the specified start time ({attrs_flash_age['start_time']})."
)
assert "All the flash_age events happened before 2024-08-01T10:00:00" in caplog.text
flash_age = xr.DataArray(flash_age_value,
dims=["y"],
coords={
"crs": "8B +proj=longlat +ellps=WGS84 +type=crs"},
attrs = attrs_flash_age,
name="flash_time")
with caplog.at_level(logging.WARNING):
_ = comp([flash_age])
# Assert that the log contains the expected warning message
assert "All the flash_age events happened before" in caplog.text

def test_update_missing_metadata():
"""Test the _update_missing_metadata method."""
Expand Down
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