fix(sat-etl): Only process native files in date range (#136)

containers/sat/download_process_sat.py

@@ -228,6 +228,14 @@ def download_scans(
 
     return files
 
+def _fname_to_scantime(fname: str) -> dt.datetime:
+    """Converts a filename to a datetime.
+
+    Files are of the form:
+    `MSG2-SEVI-MSG15-0100-NA-20230910221240.874000000Z-NA.nat`
+    So determine the time from the first element split by '.'.
+    """
+    return dt.datetime.strptime(fname.split(".")[0][-14:], "%Y%m%d%H%M%S")
 
 def process_scans(
     sat_config: Config,
@@ -256,15 +264,16 @@ def process_scans(
 
     # Get native files in order
     native_files: list[pathlib.Path] = list(folder.glob("*.nat"))
-    log.info(f"Found {len(native_files)} native files at {folder.as_posix()}")
     native_files.sort()
+    wanted_files = [f for f in native_files if start <= _fname_to_scantime(f.name).date() < end]
+    log.info(f"Found {len(wanted_files)} native files within date range at {folder.as_posix()}")
 
     # Convert native files to xarray datasets
     # * Append to the monthly zarr in hourly chunks
     datasets: list[xr.Dataset] = []
     i: int
     f: pathlib.Path
-    for i, f in enumerate(native_files):
+    for i, f in enumerate(wanted_files):
         try:
             # TODO: This method of passing the zarr times to the open function leaves a lot to be desired
             # Firstly, if the times are not passed in sorted order then the created 12-dataset chunks
@@ -301,7 +310,7 @@ def process_scans(
             )
             datasets = []
 
-        log.info(f"Process loop [{dstype}]: {i+1}/{len(native_files)}")
+        log.info(f"Process loop [{dstype}]: {i+1}/{len(wanted_files)}")
 
     # Consolidate zarr metadata
     if pathlib.Path(zarr_path).exists():
@@ -635,7 +644,10 @@ def run(args: argparse.Namespace) -> None:
     # Estimate average runtime
     secs_per_scan: int = 90
     expected_runtime = pd.Timedelta(secs_per_scan * len(scan_times), "seconds")
-    log.info(f"Downloading {len(scan_times)} scans. Expected runtime: {expected_runtime!s}")
+    log.info(
+        f"Downloading {len(scan_times)} scans ({start} - {end}). "
+        f"Expected runtime: {expected_runtime!s}"
+    )
 
     # Download data
     # We only parallelize if we have a number of files larger than the cpu count