Implement cudf.MultiIndex.from_arrays

docs/cudf/source/user_guide/api_docs/index_objects.rst

@@ -228,6 +228,7 @@ MultiIndex constructors
 .. autosummary::
    :toctree: api/
 
+   MultiIndex.from_arrays
    MultiIndex.from_tuples
    MultiIndex.from_product
    MultiIndex.from_frame

python/cudf/cudf/core/multiindex.py

@@ -27,6 +27,7 @@
 from cudf.core._compat import PANDAS_GE_150
 from cudf.core.frame import Frame
 from cudf.core.index import BaseIndex, _lexsorted_equal_range, as_index
+from cudf.utils.dtypes import is_column_like
 from cudf.utils.nvtx_annotation import _cudf_nvtx_annotate
 from cudf.utils.utils import NotIterable, _external_only_api, _is_same_name
 
@@ -1226,6 +1227,7 @@ def from_tuples(cls, tuples, names=None):
 
         See Also
         --------
+        MultiIndex.from_arrays : Convert list of arrays to MultiIndex.
         MultiIndex.from_product : Make a MultiIndex from cartesian product
                                   of iterables.
         MultiIndex.from_frame : Make a MultiIndex from a DataFrame.
@@ -1335,6 +1337,7 @@ def from_frame(cls, df, names=None):
 
         See Also
         --------
+        MultiIndex.from_arrays : Convert list of arrays to MultiIndex.
         MultiIndex.from_tuples : Convert list of tuples to MultiIndex.
         MultiIndex.from_product : Make a MultiIndex from cartesian product
                                   of iterables.
@@ -1429,6 +1432,66 @@ def from_product(cls, arrays, names=None):
         pdi = pd.MultiIndex.from_product(arrays, names=names)
         return cls.from_pandas(pdi)
 
+    @classmethod
+    @_cudf_nvtx_annotate
+    def from_arrays(
+        cls,
+        arrays,
+        sortorder=None,
+        names=None,
+    ) -> MultiIndex:
+        """
+        Convert arrays to MultiIndex.
+
+        Parameters
+        ----------
+        arrays : list / sequence of array-likes
+            Each array-like gives one level's value for each data point.
+            len(arrays) is the number of levels.
+        sortorder : optional int
+            Not yet supported
+        names : list / sequence of str, optional
+            Names for the levels in the index.
+
+        Returns
+        -------
+        MultiIndex
+
+        See Also
+        --------
+        MultiIndex.from_tuples : Convert list of tuples to MultiIndex.
+        MultiIndex.from_product : Make a MultiIndex from cartesian product
+                                  of iterables.
+        MultiIndex.from_frame : Make a MultiIndex from a DataFrame.
+
+        Examples
+        --------
+        >>> arrays = [[1, 1, 2, 2], ['red', 'blue', 'red', 'blue']]
+        >>> cudf.MultiIndex.from_arrays(arrays, names=('number', 'color'))
+        MultiIndex([(1,  'red'),
+                    (1, 'blue'),
+                    (2,  'red'),
+                    (2, 'blue')],
+                   names=['number', 'color'])
+        """
+        # Imported here due to circular import
+        from cudf.core.algorithms import factorize
+
+        error_msg = "Input must be a list / sequence of array-likes."
+        if not is_list_like(arrays):
+            raise TypeError(error_msg)
+        codes = []
+        levels = []
+        for array in arrays:
+            if not (is_list_like(array) or is_column_like(array)):
+                raise TypeError(error_msg)
+            code, level = factorize(array, sort=True)
+            codes.append(code)
+            levels.append(level)
+        return cls(
+            codes=codes, levels=levels, sortorder=sortorder, names=names
+        )
+
     @_cudf_nvtx_annotate
     def _poplevels(self, level):
         """

python/cudf/cudf/tests/test_multiindex.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2019-2023, NVIDIA CORPORATION.
+# Copyright (c) 2019-2024, NVIDIA CORPORATION.
 
 """
 Test related to MultiIndex
@@ -2085,12 +2085,7 @@ def test_multiindex_eq_other_multiindex():
     params=[
         "from_product",
         "from_tuples",
-        pytest.param(
-            "from_arrays",
-            marks=pytest.mark.xfail(
-                reason="TODO: from_arrays is not implemented"
-            ),
-        ),
+        "from_arrays",
         "init",
     ]
 )
@@ -2100,7 +2095,7 @@ def midx(request):
     elif request.param == "from_tuples":
         return cudf.MultiIndex.from_tuples([(0, 1), (0, 0), (1, 1), (1, 0)])
     elif request.param == "from_arrays":
-        return cudf.MultiIndex.from_arrays([0, 0, 1, 1], [1, 0, 1, 0])
+        return cudf.MultiIndex.from_arrays([[0, 0, 1, 1], [1, 0, 1, 0]])
     elif request.param == "init":
         return cudf.MultiIndex(
             levels=[[0, 1], [0, 1]], codes=[[0, 0, 1, 1], [1, 0, 1, 0]]
@@ -2112,3 +2107,30 @@ def midx(request):
 def test_multindex_constructor_levels_always_indexes(midx):
     assert_eq(midx.levels[0], cudf.Index([0, 1]))
     assert_eq(midx.levels[1], cudf.Index([0, 1]))
+
+
+@pytest.mark.parametrize(
+    "array",
+    [
+        list,
+        tuple,
+        np.array,
+        cp.array,
+        pd.Index,
+        cudf.Index,
+        pd.Series,
+        cudf.Series,
+    ],
+)
+def test_multiindex_from_arrays(array):
+    pd_data = [[0, 0, 1, 1], [1, 0, 1, 0]]
+    cudf_data = [array(lst) for lst in pd_data]
+    result = pd.MultiIndex.from_arrays(pd_data)
+    expected = cudf.MultiIndex.from_arrays(cudf_data)
+    assert_eq(result, expected)
+
+
+@pytest.mark.parametrize("arg", ["foo", ["foo"]])
+def test_multiindex_from_arrays_wrong_arg(arg):
+    with pytest.raises(TypeError):
+        cudf.MultiIndex.from_arrays(arg)