Use true ASCII attributes in dataframes

apis/python/src/tiledbsoma/soma_dataframe.py

@@ -5,7 +5,7 @@
 import pyarrow as pa
 import tiledb
 
-from . import util, util_arrow, util_pandas, util_tiledb
+from . import util, util_arrow, util_tiledb
 from .logging import log_io
 from .soma_collection import SOMACollectionBase
 from .tiledb_array import TileDBArray
@@ -226,7 +226,7 @@ def read(
                 # Also: don't materialize these on read
                 # TODO: get the arrow syntax for drop
                 # df.drop(ROWID, axis=1)
-                yield util_arrow.ascii_to_unicode_pyarrow_readback(table)
+                yield table
 
     def read_all(
         self,
@@ -363,7 +363,7 @@ def read_as_pandas(
                 # This is the 'decode on read' part of our logic; in dim_select we have the 'encode on
                 # write' part.
                 # Context: https://github.com/single-cell-data/TileDB-SOMA/issues/99.
-                df = util_pandas.ascii_to_unicode_pandas_readback(df)
+                df = df
 
                 if id_column_name is not None:
                     df.reset_index(inplace=True)
@@ -477,7 +477,7 @@ def write_from_pandas(
             dfc = dataframe[column_name]
             if len(dfc) > 0 and type(dfc[0]) == str:
                 # Force ASCII storage if string, in order to make obs/var columns queryable.
-                column_types[column_name] = np.dtype("S")
+                column_types[column_name] = "ascii"
 
         tiledb.from_pandas(
             uri=self.uri,

apis/python/src/tiledbsoma/soma_indexed_dataframe.py

@@ -259,11 +259,7 @@ def read(
                 iterator = query.df[ids]
 
             for table in iterator:
-                # XXX COMMENT MORE
-                # This is the 'decode on read' part of our logic; in dim_select we have the
-                # 'encode on write' part.
-                # Context: # https://github.com/single-cell-data/TileDB-SOMA/issues/99.
-                yield util_arrow.ascii_to_unicode_pyarrow_readback(table)
+                yield table
 
     def read_all(
         self,

apis/python/src/tiledbsoma/util_arrow.py

@@ -23,9 +23,7 @@
     #
     # IMPORTANT: ALL non-primitive types supported by TileDB must be in this table.
     #
-    pa.string(): np.dtype(
-        "S"
-    ),  # XXX TODO: temporary work-around until UTF8 support is native. GH #338.
+    pa.string(): "ascii",  # XXX TODO: temporary work-around until UTF8 support is native. GH #338.
     pa.binary(): np.dtype("S"),
     pa.timestamp("s"): "datetime64[s]",
     pa.timestamp("ms"): "datetime64[ms]",
@@ -39,7 +37,7 @@
 }
 
 
-def tiledb_type_from_arrow_type(t: pa.DataType) -> Union[type, np.dtype]:
+def tiledb_type_from_arrow_type(t: pa.DataType) -> Union[type, np.dtype, str]:
     """
     Given an Arrow type, return the corresponding TileDB type as a Numpy dtype.
     Building block for Arrow-to-TileDB schema translation.
@@ -61,7 +59,10 @@ def tiledb_type_from_arrow_type(t: pa.DataType) -> Union[type, np.dtype]:
         arrow_type = ARROW_TO_TDB[t]
         if isinstance(arrow_type, Exception):
             raise arrow_type
-        return np.dtype(arrow_type)
+        if arrow_type == "ascii":
+            return arrow_type
+        else:
+            return np.dtype(arrow_type)
 
     if not pa.types.is_primitive(t):
         raise TypeError(f"Type {str(t)} - unsupported type")
@@ -83,11 +84,11 @@ def tiledb_type_from_arrow_type(t: pa.DataType) -> Union[type, np.dtype]:
         raise TypeError("Unsupported Arrow type") from exc
 
 
-def get_arrow_type_from_tiledb_dtype(tiledb_dtype: np.dtype) -> pa.DataType:
+def get_arrow_type_from_tiledb_dtype(tiledb_dtype: Union[str, np.dtype]) -> pa.DataType:
     """
     TODO: COMMENT
     """
-    if tiledb_dtype.name == "bytes":
+    if tiledb_dtype == "ascii" or tiledb_dtype.name == "bytes":
         # XXX TODO: temporary work-around until UTF8 support is native. GH #338.
         return pa.string()
     else:
@@ -119,22 +120,3 @@ def get_arrow_schema_from_tiledb_uri(
             arrow_schema_dict[name] = get_arrow_type_from_tiledb_dtype(attr.dtype)
 
     return pa.schema(arrow_schema_dict)
-
-
-def ascii_to_unicode_pyarrow_readback(table: pa.Table) -> pa.Table:
-    """
-    Implements the 'decode on read' part of our ASCII/Unicode logic
-    """
-    # TODO: COMMENT/LINK HEAVILY
-    names = [ofield.name for ofield in table.schema]
-    new_fields = []
-    for name in names:
-        old_field = table[name]
-        if len(old_field) > 0 and isinstance(old_field[0], pa.LargeBinaryScalar):
-            nfield = pa.array(
-                [element.as_py().decode("utf-8") for element in old_field]
-            )
-            new_fields.append(nfield)
-        else:
-            new_fields.append(old_field)
-    return pa.Table.from_arrays(new_fields, names=names)

apis/python/tests/test_type_system.py

@@ -65,7 +65,7 @@ def test_supported_types_supported(arrow_type):
         pytest.xfail("Awaiting UTF-8 support - see issue #338")
 
     tdb_dtype = tiledb_type_from_arrow_type(arrow_type)
-    assert isinstance(tdb_dtype, np.dtype)
+    assert isinstance(tdb_dtype, np.dtype) or tdb_dtype == "ascii"
     rt_arrow_type = get_arrow_type_from_tiledb_dtype(tdb_dtype)
     assert isinstance(rt_arrow_type, pa.DataType)
     assert arrow_type == rt_arrow_type