Loads of small cleanups (#203)

* Loads of cleanups

* Better docstrings.

* Pylint warnings (wth pre-commit)

* But actually do the TODO this time.

src/hipscat_import/catalog/map_reduce.py

@@ -8,34 +8,16 @@
 import pyarrow.parquet as pq
 from hipscat import pixel_math
 from hipscat.io import FilePointer, file_io, paths
+from hipscat.pixel_math.healpix_pixel import HealpixPixel
 from hipscat.pixel_math.hipscat_id import HIPSCAT_ID_COLUMN, hipscat_id_to_healpix
 
 from hipscat_import.catalog.file_readers import InputReader
 from hipscat_import.catalog.resume_plan import ResumePlan
+from hipscat_import.pipeline_resume_plan import get_pixel_cache_directory
 
 # pylint: disable=too-many-locals,too-many-arguments
 
 
-def _get_pixel_directory(cache_path: FilePointer, order: np.int64, pixel: np.uint64):
-    """Create a path for intermediate pixel data.
-
-    This will take the form:
-
-        <cache_path>/dir_<directory separator>/pixel_<pixel>
-
-    where the directory separator is calculated using integer division:
-
-        (pixel/10000)*10000
-
-    and exists to mitigate problems on file systems that don't support
-    more than 10_000 children nodes.
-    """
-    dir_number = int(pixel / 10_000) * 10_000
-    return file_io.append_paths_to_pointer(
-        cache_path, f"order_{order}", f"dir_{dir_number}", f"pixel_{pixel}"
-    )
-
-
 def _has_named_index(dataframe):
     """Heuristic to determine if a dataframe has some meaningful index.
 
@@ -172,7 +154,7 @@ def split_pixels(
 
             filtered_data = data.filter(items=data_indexes, axis=0)
 
-            pixel_dir = _get_pixel_directory(cache_shard_path, order, pixel)
+            pixel_dir = get_pixel_cache_directory(cache_shard_path, HealpixPixel(order, pixel))
             file_io.make_directory(pixel_dir, exist_ok=True)
             output_file = file_io.append_paths_to_pointer(
                 pixel_dir, f"shard_{splitting_key}_{chunk_number}.parquet"
@@ -259,7 +241,8 @@ def reduce_pixel_shards(
         ).schema.to_arrow_schema()
 
     tables = []
-    pixel_dir = _get_pixel_directory(cache_shard_path, destination_pixel_order, destination_pixel_number)
+    healpix_pixel = HealpixPixel(destination_pixel_order, destination_pixel_number)
+    pixel_dir = get_pixel_cache_directory(cache_shard_path, healpix_pixel)
 
     if schema:
         tables.append(pq.read_table(pixel_dir, schema=schema))
@@ -273,7 +256,7 @@ def reduce_pixel_shards(
     if rows_written != destination_pixel_size:
         raise ValueError(
             "Unexpected number of objects at pixel "
-            f"({destination_pixel_order}, {destination_pixel_number})."
+            f"({healpix_pixel})."
             f" Expected {destination_pixel_size}, wrote {rows_written}"
         )
 
@@ -286,13 +269,9 @@ def reduce_pixel_shards(
             dataframe[dec_column].values,
         )
 
-    dataframe["Norder"] = np.full(rows_written, fill_value=destination_pixel_order, dtype=np.uint8)
-    dataframe["Dir"] = np.full(
-        rows_written,
-        fill_value=int(destination_pixel_number / 10_000) * 10_000,
-        dtype=np.uint64,
-    )
-    dataframe["Npix"] = np.full(rows_written, fill_value=destination_pixel_number, dtype=np.uint64)
+    dataframe["Norder"] = np.full(rows_written, fill_value=healpix_pixel.order, dtype=np.uint8)
+    dataframe["Dir"] = np.full(rows_written, fill_value=healpix_pixel.dir, dtype=np.uint64)
+    dataframe["Npix"] = np.full(rows_written, fill_value=healpix_pixel.pixel, dtype=np.uint64)
 
     if add_hipscat_index:
         ## If we had a meaningful index before, preserve it as a column.
@@ -304,7 +283,7 @@ def reduce_pixel_shards(
     del dataframe, merged_table, tables
 
     if delete_input_files:
-        pixel_dir = _get_pixel_directory(cache_shard_path, destination_pixel_order, destination_pixel_number)
+        pixel_dir = get_pixel_cache_directory(cache_shard_path, healpix_pixel)
 
         file_io.remove_directory(pixel_dir, ignore_errors=True, storage_options=storage_options)