Add string.convert.convert_fixed_type APIs to pylibcudf (#16984)

Contributes to #15162

Authors:
  - Matthew Roeschke (https://github.com/mroeschke)

Approvers:
  - Vyas Ramasubramani (https://github.com/vyasr)

URL: #16984

python/cudf/cudf/_lib/strings/convert/convert_fixed_point.pyx

@@ -1,22 +1,11 @@
 # Copyright (c) 2021-2024, NVIDIA CORPORATION.
 
-import cudf
-
-from libcpp.memory cimport unique_ptr
-from libcpp.utility cimport move
-
 from cudf.core.buffer import acquire_spill_lock
 
-from pylibcudf.libcudf.column.column cimport column
-from pylibcudf.libcudf.column.column_view cimport column_view
-from pylibcudf.libcudf.strings.convert.convert_fixed_point cimport (
-    from_fixed_point as cpp_from_fixed_point,
-    is_fixed_point as cpp_is_fixed_point,
-    to_fixed_point as cpp_to_fixed_point,
-)
-from pylibcudf.libcudf.types cimport data_type, type_id
-
 from cudf._lib.column cimport Column
+from cudf._lib.types cimport dtype_to_pylibcudf_type
+
+import pylibcudf as plc
 
 
 @acquire_spill_lock()
@@ -32,14 +21,10 @@ def from_decimal(Column input_col):
     -------
     A column of strings representing the input decimal values.
     """
-    cdef column_view input_column_view = input_col.view()
-    cdef unique_ptr[column] c_result
-    with nogil:
-        c_result = move(
-            cpp_from_fixed_point(
-                input_column_view))
-
-    return Column.from_unique_ptr(move(c_result))
+    plc_column = plc.strings.convert.convert_fixed_point.from_fixed_point(
+        input_col.to_pylibcudf(mode="read"),
+    )
+    return Column.from_pylibcudf(plc_column)
 
 
 @acquire_spill_lock()
@@ -57,25 +42,11 @@ def to_decimal(Column input_col, object out_type):
     -------
     A column of decimals parsed from the string values.
     """
-    cdef column_view input_column_view = input_col.view()
-    cdef unique_ptr[column] c_result
-    cdef int scale = out_type.scale
-    cdef data_type c_out_type
-    if isinstance(out_type, cudf.Decimal32Dtype):
-        c_out_type = data_type(type_id.DECIMAL32, -scale)
-    elif isinstance(out_type, cudf.Decimal64Dtype):
-        c_out_type = data_type(type_id.DECIMAL64, -scale)
-    elif isinstance(out_type, cudf.Decimal128Dtype):
-        c_out_type = data_type(type_id.DECIMAL128, -scale)
-    else:
-        raise TypeError("should be a decimal dtype")
-    with nogil:
-        c_result = move(
-            cpp_to_fixed_point(
-                input_column_view,
-                c_out_type))
-
-    result = Column.from_unique_ptr(move(c_result))
+    plc_column = plc.strings.convert.convert_fixed_point.to_fixed_point(
+        input_col.to_pylibcudf(mode="read"),
+        dtype_to_pylibcudf_type(out_type),
+    )
+    result = Column.from_pylibcudf(plc_column)
     result.dtype.precision = out_type.precision
     return result
 
@@ -98,14 +69,8 @@ def is_fixed_point(Column input_col, object dtype):
     -------
     A Column of booleans indicating valid decimal conversion.
     """
-    cdef unique_ptr[column] c_result
-    cdef column_view source_view = input_col.view()
-    cdef int scale = dtype.scale
-    cdef data_type c_dtype = data_type(type_id.DECIMAL64, -scale)
-    with nogil:
-        c_result = move(cpp_is_fixed_point(
-            source_view,
-            c_dtype
-        ))
-
-    return Column.from_unique_ptr(move(c_result))
+    plc_column = plc.strings.convert.convert_fixed_point.is_fixed_point(
+        input_col.to_pylibcudf(mode="read"),
+        dtype_to_pylibcudf_type(dtype),
+    )
+    return Column.from_pylibcudf(plc_column)

python/pylibcudf/pylibcudf/libcudf/strings/convert/convert_fixed_point.pxd

@@ -9,13 +9,13 @@ from pylibcudf.libcudf.types cimport data_type
 cdef extern from "cudf/strings/convert/convert_fixed_point.hpp" namespace \
         "cudf::strings" nogil:
     cdef unique_ptr[column] to_fixed_point(
-        column_view input_col,
+        column_view input,
         data_type output_type) except +
 
     cdef unique_ptr[column] from_fixed_point(
-        column_view input_col) except +
+        column_view input) except +
 
     cdef unique_ptr[column] is_fixed_point(
-        column_view source_strings,
-        data_type output_type
+        column_view input,
+        data_type decimal_type
     ) except +

python/pylibcudf/pylibcudf/strings/convert/CMakeLists.txt

@@ -12,7 +12,9 @@
 # the License.
 # =============================================================================
 
-set(cython_sources convert_booleans.pyx convert_durations.pyx convert_datetime.pyx)
+set(cython_sources convert_booleans.pyx convert_datetime.pyx convert_durations.pyx
+                   convert_fixed_point.pyx
+)
 
 set(linked_libraries cudf::cudf)
 rapids_cython_create_modules(

python/pylibcudf/pylibcudf/strings/convert/__init__.pxd

@@ -1,2 +1,7 @@
 # Copyright (c) 2024, NVIDIA CORPORATION.
-from . cimport convert_booleans, convert_datetime, convert_durations
+from . cimport (
+    convert_booleans,
+    convert_datetime,
+    convert_durations,
+    convert_fixed_point,
+)

python/pylibcudf/pylibcudf/strings/convert/__init__.py

@@ -1,2 +1,7 @@
 # Copyright (c) 2024, NVIDIA CORPORATION.
-from . import convert_booleans, convert_datetime, convert_durations
+from . import (
+    convert_booleans,
+    convert_datetime,
+    convert_durations,
+    convert_fixed_point,
+)

python/pylibcudf/pylibcudf/strings/convert/convert_fixed_point.pxd

@@ -0,0 +1,11 @@
+# Copyright (c) 2024, NVIDIA CORPORATION.
+
+from pylibcudf.column cimport Column
+from pylibcudf.types cimport DataType
+
+
+cpdef Column to_fixed_point(Column input, DataType output_type)
+
+cpdef Column from_fixed_point(Column input)
+
+cpdef Column is_fixed_point(Column input, DataType decimal_type=*)

python/pylibcudf/pylibcudf/strings/convert/convert_fixed_point.pyx

@@ -0,0 +1,107 @@
+# Copyright (c) 2024, NVIDIA CORPORATION.
+
+from libcpp.memory cimport unique_ptr
+from libcpp.utility cimport move
+from pylibcudf.column cimport Column
+from pylibcudf.libcudf.column.column cimport column
+from pylibcudf.libcudf.strings.convert cimport (
+    convert_fixed_point as cpp_fixed_point,
+)
+from pylibcudf.types cimport DataType, type_id
+
+
+cpdef Column to_fixed_point(Column input, DataType output_type):
+    """
+    Returns a new fixed-point column parsing decimal values from the
+    provided strings column.
+
+    For details, see :cpp:details:`cudf::strings::to_fixed_point`
+
+    Parameters
+    ----------
+    input : Column
+        Strings instance for this operation.
+
+    output_type : DataType
+        Type of fixed-point column to return including the scale value.
+
+    Returns
+    -------
+    Column
+        New column of output_type.
+    """
+    cdef unique_ptr[column] c_result
+
+    with nogil:
+        c_result = move(
+            cpp_fixed_point.to_fixed_point(
+                input.view(),
+                output_type.c_obj,
+            )
+        )
+
+    return Column.from_libcudf(move(c_result))
+
+cpdef Column from_fixed_point(Column input):
+    """
+    Returns a new strings column converting the fixed-point values
+    into a strings column.
+
+    For details, see :cpp:details:`cudf::strings::from_fixed_point`
+
+    Parameters
+    ----------
+    input : Column
+        Fixed-point column to convert.
+
+    Returns
+    -------
+    Column
+        New strings column.
+    """
+    cdef unique_ptr[column] c_result
+
+    with nogil:
+        c_result = move(
+            cpp_fixed_point.from_fixed_point(
+                input.view(),
+            )
+        )
+
+    return Column.from_libcudf(move(c_result))
+
+cpdef Column is_fixed_point(Column input, DataType decimal_type=None):
+    """
+    Returns a boolean column identifying strings in which all
+    characters are valid for conversion to fixed-point.
+
+    For details, see :cpp:details:`cudf::strings::is_fixed_point`
+
+    Parameters
+    ----------
+    input : Column
+        Strings instance for this operation.
+
+    decimal_type : DataType
+        Fixed-point type (with scale) used only for checking overflow.
+        Defaults to Decimal64
+
+    Returns
+    -------
+    Column
+        New column of boolean results for each string.
+    """
+    cdef unique_ptr[column] c_result
+
+    if decimal_type is None:
+        decimal_type = DataType(type_id.DECIMAL64)
+
+    with nogil:
+        c_result = move(
+            cpp_fixed_point.is_fixed_point(
+                input.view(),
+                decimal_type.c_obj,
+            )
+        )
+
+    return Column.from_libcudf(move(c_result))

python/pylibcudf/pylibcudf/tests/test_string_convert_fixed_point.py

@@ -0,0 +1,34 @@
+# Copyright (c) 2024, NVIDIA CORPORATION.
+import decimal
+
+import pyarrow as pa
+import pylibcudf as plc
+from utils import assert_column_eq
+
+
+def test_to_fixed_point():
+    typ = pa.decimal128(38, 2)
+    arr = pa.array(["123", "1.23", None])
+    result = plc.strings.convert.convert_fixed_point.to_fixed_point(
+        plc.interop.from_arrow(arr), plc.interop.from_arrow(typ)
+    )
+    expected = arr.cast(typ)
+    assert_column_eq(result, expected)
+
+
+def test_from_fixed_point():
+    arr = pa.array([decimal.Decimal("1.1"), None])
+    result = plc.strings.convert.convert_fixed_point.from_fixed_point(
+        plc.interop.from_arrow(arr),
+    )
+    expected = pa.array(["1.1", None])
+    assert_column_eq(result, expected)
+
+
+def test_is_fixed_point():
+    arr = pa.array(["123", "1.23", "1.2.3", "", None])
+    result = plc.strings.convert.convert_fixed_point.is_fixed_point(
+        plc.interop.from_arrow(arr),
+    )
+    expected = pa.array([True, True, False, False, None])
+    assert_column_eq(result, expected)