Drop Ping Time Duplicates (OSOceanAcoustics#1382)

* init commit

* revert change to fix merge conflict

* test only one file

* use other file

* move test duplicate to test convert ek

* add extra line

* move test back to ek80 convert

* pin zarr and add check unique ping time duplicates and tests

* fix test message

* test remove zarr pin

* add back zarr pin

echopype/convert/set_groups_ek80.py

@@ -8,6 +8,7 @@
 from ..utils.coding import set_time_encodings
 from ..utils.log import _init_logger
 from .set_groups_base import SetGroupsBase
+from .utils.ek_duplicates import check_unique_ping_time_duplicates
 
 logger = _init_logger(__name__)
 
@@ -1145,6 +1146,17 @@ def set_beam(self) -> List[xr.Dataset]:
 
             ds_data = self._attach_vars_to_ds_data(ds_data, ch, rs_size=ds_data.range_sample.size)
 
+            # Access the 'ping_time' coordinate as a NumPy array
+            ping_times = ds_data["ping_time"].values
+
+            # Check if ping time duplicates exist
+            if len(ping_times) > len(np.unique(ping_times)):
+                # Check for unique ping time duplicates and if they are not unique, raise warning.
+                check_unique_ping_time_duplicates(ds_data, logger)
+
+                # Drop duplicates
+                ds_data = ds_data.drop_duplicates(dim="ping_time")
+
             if ch in self.sorted_channel["complex"]:
                 ds_complex.append(ds_data)
             else:

echopype/convert/utils/ek_duplicates.py

@@ -0,0 +1,44 @@
+import logging
+
+import xarray as xr
+
+
+def check_unique_ping_time_duplicates(ds_data: xr.Dataset, logger: logging.Logger) -> None:
+    """
+    Raises a warning if the data stored in duplicate pings is not unique.
+
+    Parameters
+    ----------
+    ds_data : xr.Dataset
+        Single freq beam dataset being processed in the `SetGroupsEK80.set_beams` class function.
+    logger : logging.Logger
+        Warning logger initialized in `SetGroupsEK80` file.
+    """
+    # Group the dataset by the "ping_time" coordinate
+    groups = ds_data.groupby("ping_time")
+
+    # Loop through each ping_time group
+    for ping_time_val, group in groups:
+        # Extract all data variable names to check
+        data_vars = list(group.data_vars)
+
+        # Use the first duplicate ping time index as a reference
+        ref_duplicate_ping_time_index = 0
+
+        # Iterate over each data variable in the group
+        for var in data_vars:
+            # Extract data array corresponding to the iterated variable
+            data_array = group[var]
+
+            # Use the slice corresponding to the reference index as the reference slice
+            ref_slice = data_array.isel({"ping_time": ref_duplicate_ping_time_index})
+
+            # Iterate over the remaining entries
+            for i in range(1, data_array.sizes["ping_time"]):
+                if not ref_slice.equals(data_array.isel({"ping_time": i})):
+                    logger.warning(
+                        f"Duplicate slices in variable '{var}' corresponding to 'ping_time' "
+                        f"{ping_time_val} differ in data. All duplicate 'ping_time' entries "
+                        "will be removed, which will result in data loss."
+                    )
+                    break

echopype/tests/convert/test_convert_ek80.py

@@ -4,11 +4,14 @@
 import numpy as np
 import pandas as pd
 from scipy.io import loadmat
+import xarray as xr
 
 from echopype import open_raw, open_converted
 from echopype.testing import TEST_DATA_FOLDER
 from echopype.convert.parse_ek80 import ParseEK80
 from echopype.convert.set_groups_ek80 import WIDE_BAND_TRANS, PULSE_COMPRESS, FILTER_IMAG, FILTER_REAL, DECIMATION
+from echopype.utils import log
+from echopype.convert.utils.ek_duplicates import check_unique_ping_time_duplicates
 
 
 @pytest.fixture
@@ -512,6 +515,62 @@ def test_parse_missing_sound_velocity_profile():
     shutil.rmtree(save_path)
 
 
+@pytest.mark.unit
+def test_duplicate_ping_times(caplog):
+    """
+    Tests that RAW file with duplicate ping times can be parsed and that the correct warning has been raised.
+    """
+    # Turn on logger verbosity
+    log.verbose(override=False)
+
+    # Open RAW
+    ed = open_raw("echopype/test_data/ek80_duplicate_ping_times/Hake-D20210913-T130612.raw", sonar_model="EK80")
+
+    # Check that there are no ping time duplicates in Beam group
+    assert ed["Sonar/Beam_group1"].equals(
+        ed["Sonar/Beam_group1"].drop_duplicates(dim="ping_time")
+    )
+
+    # Check that no warning is logged since the data for all duplicate pings is unique
+    not_expected_warning = ("All duplicate ping_time entries' will be removed, resulting in potential data loss.")
+    assert not any(not_expected_warning in record.message for record in caplog.records)
+
+    # Turn off logger verbosity
+    log.verbose(override=True)
+
+
+@pytest.mark.unit
+def test_check_unique_ping_time_duplicates(caplog):
+    """
+    Checks that `check_unique_ping_time_duplicates` raises a warning when the data for duplicate ping times is not unique.
+    """
+    # Initialize logger
+    logger = log._init_logger(__name__)
+
+    # Turn on logger verbosity
+    log.verbose(override=False)
+
+    # Open duplicate ping time beam dataset
+    ds_data = xr.open_zarr("echopype/test_data/ek80_duplicate_ping_times/duplicate_beam_ds.zarr")
+
+    # Modify a single entry to ensure that there exists duplicate ping times that do not share the same backscatter data
+    ds_data["backscatter_r"][0,0,0] = 0
+
+    # Check for ping time duplicates
+    check_unique_ping_time_duplicates(ds_data, logger)
+
+    # Turn off logger verbosity
+    log.verbose(override=True)
+
+    # Check if the expected warning is logged
+    expected_warning = (
+        "Duplicate slices in variable 'backscatter_r' corresponding to 'ping_time' "
+        f"{str(ds_data['ping_time'].values[0])} differ in data. All duplicate "
+        "'ping_time' entries will be removed, which will result in data loss."
+    )
+    assert any(expected_warning in record.message for record in caplog.records)
+
+
 @pytest.mark.unit
 def test_parse_ek80_with_invalid_env_datagrams():
     """