ak.fields (#1296)

src/awkward/_v2/operations/describe/ak_fields.py

@@ -7,22 +7,20 @@
 
 
 def fields(array):
-    raise NotImplementedError
 
-
-#     """
-#     Extracts record fields or tuple slot numbers from `array` (many types
-#     supported, including all Awkward Arrays and Records).
-
-#     If the array contains nested records, only the outermost record is
-#     queried. If it contains tuples instead of records, this function outputs
-#     string representations of integers, such as `"0"`, `"1"`, `"2"`, etc.
-#     The records or tuples may be within multiple layers of nested lists.
-
-#     If the array contains neither tuples nor records, this returns an empty
-#     list.
-#     """
-#     layout = ak._v2.operations.convert.to_layout(
-#         array, allow_record=True, allow_other=False
-#     )
-#     return layout.keys()
+    """
+    Extracts record fields or tuple slot numbers from `array` (many types
+    supported, including all Awkward Arrays and Records).
+
+    If the array contains nested records, only the outermost record is
+    queried. If it contains tuples instead of records, this function outputs
+    string representations of integers, such as `"0"`, `"1"`, `"2"`, etc.
+    The records or tuples may be within multiple layers of nested lists.
+
+    If the array contains neither tuples nor records, this returns an empty
+    list.
+    """
+    layout = ak._v2.operations.convert.to_layout(
+        array, allow_record=True, allow_other=False
+    )
+    return layout.fields

tests/v2/test_0273-path-for-with-field.py

@@ -9,14 +9,6 @@
 
 
 def test_one_level():
-
-    base = ak.zip({"a": ak.zip({"x": [1, 2, 3]}), "b": [1, 2, 3]}, depth_limit=1)
-    what = ak.Array([1.1, 2.2, 3.3], check_valid=True)
-    assert ak.to_list(ak.with_field(base, what, where=["a", "y"])) == [
-        {"b": 1, "a": {"x": 1, "y": 1.1}},
-        {"b": 2, "a": {"x": 2, "y": 2.2}},
-        {"b": 3, "a": {"x": 3, "y": 3.3}},
-    ]
     base = ak._v2.operations.structure.zip(
         {"a": ak._v2.operations.structure.zip({"x": [1, 2, 3]}), "b": [1, 2, 3]},
         depth_limit=1,
@@ -29,6 +21,7 @@ def test_one_level():
         {"b": 2, "a": {"x": 2, "y": 2.2}},
         {"b": 3, "a": {"x": 3, "y": 3.3}},
     ]
+    assert ak._v2.operations.describe.fields(base) == ["a", "b"]
 
     base["a", "y"] = what
     assert to_list(base) == [
@@ -56,6 +49,7 @@ def test_two_level():
         {"B": 2, "A": {"b": 2, "a": {"x": 2, "y": 2.2}}},
         {"B": 3, "A": {"b": 3, "a": {"x": 3, "y": 3.3}}},
     ]
+    assert ak._v2.operations.describe.fields(base) == ["A", "B"]
 
     base["A", "a", "y"] = what
     assert to_list(base) == [
@@ -77,6 +71,7 @@ def test_replace_the_only_field():
         {"a": {"x": 2, "y": 2.2}},
         {"a": {"x": 3, "y": 3.3}},
     ]
+    assert ak._v2.operations.describe.fields(base) == ["a"]
 
     base["a", "y"] = what
     assert to_list(base) == [
@@ -110,9 +105,9 @@ def test_check_no_field():
         (2, 2.2),
         (3, 3.3),
     ]
-
     assert to_list(ak._v2.operations.structure.with_field(recordarray, what, "a")) == [
         {"0": 1, "a": 1.1},
         {"0": 2, "a": 2.2},
         {"0": 3, "a": 3.3},
     ]
+    assert ak._v2.operations.describe.fields(recordarray) == ["0"]

tests/v2/test_0286-broadcast-single-value-with-field.py

@@ -18,3 +18,10 @@ def test_broadcast_single_bool():
         base_new1, base.x > 0.3, "sometimes_true"
     )
     assert to_list(base_new2.always_true) == [[True, True]]
+    assert ak._v2.operations.describe.fields(base_new2) == [
+        "x",
+        "y",
+        "z",
+        "always_true",
+        "sometimes_true",
+    ]

tests/v2/test_0879-non-primitive-with-field.py

@@ -28,3 +28,4 @@ def test_in_place_wrapper_broadcasting():
     array["unknown field"] = None
 
     assert array["unknown field"].tolist() == [None, None, None]
+    assert ak._v2.operations.describe.fields(array) == ["x", "unknown field"]