TST/REF: implement tests.frame.constructors (pandas-dev#38869)

Author: jbrockmendel

pandas/tests/frame/constructors/__init__.py

@@ -0,0 +1,186 @@
+from collections import OrderedDict
+
+import numpy as np
+import pytest
+
+from pandas import DataFrame, Index, MultiIndex, Series
+import pandas._testing as tm
+from pandas.core.construction import create_series_with_explicit_dtype
+
+
+class TestFromDict:
+    # Note: these tests are specific to the from_dict method, not for
+    #  passing dictionaries to DataFrame.__init__
+
+    def test_from_dict_scalars_requires_index(self):
+        msg = "If using all scalar values, you must pass an index"
+        with pytest.raises(ValueError, match=msg):
+            DataFrame.from_dict(OrderedDict([("b", 8), ("a", 5), ("a", 6)]))
+
+    def test_constructor_list_of_odicts(self):
+        data = [
+            OrderedDict([["a", 1.5], ["b", 3], ["c", 4], ["d", 6]]),
+            OrderedDict([["a", 1.5], ["b", 3], ["d", 6]]),
+            OrderedDict([["a", 1.5], ["d", 6]]),
+            OrderedDict(),
+            OrderedDict([["a", 1.5], ["b", 3], ["c", 4]]),
+            OrderedDict([["b", 3], ["c", 4], ["d", 6]]),
+        ]
+
+        result = DataFrame(data)
+        expected = DataFrame.from_dict(
+            dict(zip(range(len(data)), data)), orient="index"
+        )
+        tm.assert_frame_equal(result, expected.reindex(result.index))
+
+    def test_constructor_single_row(self):
+        data = [OrderedDict([["a", 1.5], ["b", 3], ["c", 4], ["d", 6]])]
+
+        result = DataFrame(data)
+        expected = DataFrame.from_dict(dict(zip([0], data)), orient="index").reindex(
+            result.index
+        )
+        tm.assert_frame_equal(result, expected)
+
+    def test_constructor_list_of_series(self):
+        data = [
+            OrderedDict([["a", 1.5], ["b", 3.0], ["c", 4.0]]),
+            OrderedDict([["a", 1.5], ["b", 3.0], ["c", 6.0]]),
+        ]
+        sdict = OrderedDict(zip(["x", "y"], data))
+        idx = Index(["a", "b", "c"])
+
+        # all named
+        data2 = [
+            Series([1.5, 3, 4], idx, dtype="O", name="x"),
+            Series([1.5, 3, 6], idx, name="y"),
+        ]
+        result = DataFrame(data2)
+        expected = DataFrame.from_dict(sdict, orient="index")
+        tm.assert_frame_equal(result, expected)
+
+        # some unnamed
+        data2 = [
+            Series([1.5, 3, 4], idx, dtype="O", name="x"),
+            Series([1.5, 3, 6], idx),
+        ]
+        result = DataFrame(data2)
+
+        sdict = OrderedDict(zip(["x", "Unnamed 0"], data))
+        expected = DataFrame.from_dict(sdict, orient="index")
+        tm.assert_frame_equal(result, expected)
+
+        # none named
+        data = [
+            OrderedDict([["a", 1.5], ["b", 3], ["c", 4], ["d", 6]]),
+            OrderedDict([["a", 1.5], ["b", 3], ["d", 6]]),
+            OrderedDict([["a", 1.5], ["d", 6]]),
+            OrderedDict(),
+            OrderedDict([["a", 1.5], ["b", 3], ["c", 4]]),
+            OrderedDict([["b", 3], ["c", 4], ["d", 6]]),
+        ]
+        data = [
+            create_series_with_explicit_dtype(d, dtype_if_empty=object) for d in data
+        ]
+
+        result = DataFrame(data)
+        sdict = OrderedDict(zip(range(len(data)), data))
+        expected = DataFrame.from_dict(sdict, orient="index")
+        tm.assert_frame_equal(result, expected.reindex(result.index))
+
+        result2 = DataFrame(data, index=np.arange(6))
+        tm.assert_frame_equal(result, result2)
+
+        result = DataFrame([Series(dtype=object)])
+        expected = DataFrame(index=[0])
+        tm.assert_frame_equal(result, expected)
+
+        data = [
+            OrderedDict([["a", 1.5], ["b", 3.0], ["c", 4.0]]),
+            OrderedDict([["a", 1.5], ["b", 3.0], ["c", 6.0]]),
+        ]
+        sdict = OrderedDict(zip(range(len(data)), data))
+
+        idx = Index(["a", "b", "c"])
+        data2 = [Series([1.5, 3, 4], idx, dtype="O"), Series([1.5, 3, 6], idx)]
+        result = DataFrame(data2)
+        expected = DataFrame.from_dict(sdict, orient="index")
+        tm.assert_frame_equal(result, expected)
+
+    def test_constructor_orient(self, float_string_frame):
+        data_dict = float_string_frame.T._series
+        recons = DataFrame.from_dict(data_dict, orient="index")
+        expected = float_string_frame.reindex(index=recons.index)
+        tm.assert_frame_equal(recons, expected)
+
+        # dict of sequence
+        a = {"hi": [32, 3, 3], "there": [3, 5, 3]}
+        rs = DataFrame.from_dict(a, orient="index")
+        xp = DataFrame.from_dict(a).T.reindex(list(a.keys()))
+        tm.assert_frame_equal(rs, xp)
+
+    def test_constructor_from_ordered_dict(self):
+        # GH#8425
+        a = OrderedDict(
+            [
+                ("one", OrderedDict([("col_a", "foo1"), ("col_b", "bar1")])),
+                ("two", OrderedDict([("col_a", "foo2"), ("col_b", "bar2")])),
+                ("three", OrderedDict([("col_a", "foo3"), ("col_b", "bar3")])),
+            ]
+        )
+        expected = DataFrame.from_dict(a, orient="columns").T
+        result = DataFrame.from_dict(a, orient="index")
+        tm.assert_frame_equal(result, expected)
+
+    def test_from_dict_columns_parameter(self):
+        # GH#18529
+        # Test new columns parameter for from_dict that was added to make
+        # from_items(..., orient='index', columns=[...]) easier to replicate
+        result = DataFrame.from_dict(
+            OrderedDict([("A", [1, 2]), ("B", [4, 5])]),
+            orient="index",
+            columns=["one", "two"],
+        )
+        expected = DataFrame([[1, 2], [4, 5]], index=["A", "B"], columns=["one", "two"])
+        tm.assert_frame_equal(result, expected)
+
+        msg = "cannot use columns parameter with orient='columns'"
+        with pytest.raises(ValueError, match=msg):
+            DataFrame.from_dict(
+                {"A": [1, 2], "B": [4, 5]},
+                orient="columns",
+                columns=["one", "two"],
+            )
+        with pytest.raises(ValueError, match=msg):
+            DataFrame.from_dict({"A": [1, 2], "B": [4, 5]}, columns=["one", "two"])
+
+    @pytest.mark.parametrize(
+        "data_dict, keys, orient",
+        [
+            ({}, [], "index"),
+            ([{("a",): 1}, {("a",): 2}], [("a",)], "columns"),
+            ([OrderedDict([(("a",), 1), (("b",), 2)])], [("a",), ("b",)], "columns"),
+            ([{("a", "b"): 1}], [("a", "b")], "columns"),
+        ],
+    )
+    def test_constructor_from_dict_tuples(self, data_dict, keys, orient):
+        # GH#16769
+        df = DataFrame.from_dict(data_dict, orient)
+
+        result = df.columns
+        expected = Index(keys, dtype="object", tupleize_cols=False)
+
+        tm.assert_index_equal(result, expected)
+
+    def test_frame_dict_constructor_empty_series(self):
+        s1 = Series(
+            [1, 2, 3, 4], index=MultiIndex.from_tuples([(1, 2), (1, 3), (2, 2), (2, 4)])
+        )
+        s2 = Series(
+            [1, 2, 3, 4], index=MultiIndex.from_tuples([(1, 2), (1, 3), (3, 2), (3, 4)])
+        )
+        s3 = Series(dtype=object)
+
+        # it works!
+        DataFrame({"foo": s1, "bar": s2, "baz": s3})
+        DataFrame.from_dict({"foo": s1, "baz": s3, "bar": s2})