Add dataframe_regression fixture (#35)

* Add dataframe_regression fixture

* updates dataframe_regression stuff and CHANGELOG

* Allow str arrays on dataframe/num regression

CHANGELOG.rst

@@ -1,3 +1,8 @@
+2.1.0 (UNRELEASED)
+------------------
+
+* `#35 <https://github.com/ESSS/pytest-regressions/pull/35>`__: New ``dataframe_regression`` fixture to check pandas DataFrames directly.
+
 2.0.2 (2020-10-07)
 ------------------
 

doc/api.rst

@@ -8,6 +8,12 @@ data_regression
 .. automethod:: pytest_regressions.data_regression.DataRegressionFixture.check
 
 
+dataframe_regression
+--------------------
+
+.. automethod:: pytest_regressions.dataframe_regression.DataFrameRegressionFixture.check
+
+
 file_regression
 ---------------
 

src/pytest_regressions/dataframe_regression.py

@@ -0,0 +1,261 @@
+from pytest_regressions.common import perform_regression_check, import_error_message
+
+
+class DataFrameRegressionFixture:
+    """
+    Pandas DataFrame Regression fixture implementation used on dataframe_regression fixture.
+    """
+
+    DISPLAY_PRECISION = 17  # Decimal places
+    DISPLAY_WIDTH = 1000  # Max. Chars on outputs
+    DISPLAY_MAX_COLUMNS = 1000  # Max. Number of columns (see #3)
+
+    def __init__(self, datadir, original_datadir, request):
+        """
+        :type datadir: Path
+        :type original_datadir: Path
+        :type request: FixtureRequest
+        """
+        self._tolerances_dict = {}
+        self._default_tolerance = {}
+
+        self.request = request
+        self.datadir = datadir
+        self.original_datadir = original_datadir
+        self._force_regen = False
+
+        self._pandas_display_options = (
+            "display.precision",
+            DataFrameRegressionFixture.DISPLAY_PRECISION,
+            "display.width",
+            DataFrameRegressionFixture.DISPLAY_WIDTH,
+            "display.max_columns",
+            DataFrameRegressionFixture.DISPLAY_MAX_COLUMNS,
+        )
+
+    def _check_data_types(self, key, obtained_column, expected_column):
+        """
+        Check if data type of obtained and expected columns are the same. Fail if not.
+        Helper method used in _check_fn method.
+        """
+        try:
+            import numpy as np
+        except ModuleNotFoundError:
+            raise ModuleNotFoundError(import_error_message("Numpy"))
+
+        __tracebackhide__ = True
+        obtained_data_type = obtained_column.values.dtype
+        expected_data_type = expected_column.values.dtype
+        if obtained_data_type != expected_data_type:
+            # Check if both data types are comparable as numbers (float, int, short, bytes, etc...)
+            if np.issubdtype(obtained_data_type, np.number) and np.issubdtype(
+                expected_data_type, np.number
+            ):
+                return
+
+            # In case they are not, assume they are not comparable
+            error_msg = (
+                "Data type for data %s of obtained and expected are not the same.\n"
+                "Obtained: %s\n"
+                "Expected: %s\n" % (key, obtained_data_type, expected_data_type)
+            )
+            raise AssertionError(error_msg)
+
+    def _check_data_shapes(self, obtained_column, expected_column):
+        """
+        Check if obtained and expected columns have the same size.
+        Helper method used in _check_fn method.
+        """
+        __tracebackhide__ = True
+
+        obtained_data_shape = obtained_column.values.shape
+        expected_data_shape = expected_column.values.shape
+        if obtained_data_shape != expected_data_shape:
+            error_msg = (
+                "Obtained and expected data shape are not the same.\n"
+                "Obtained: %s\n"
+                "Expected: %s\n" % (obtained_data_shape, expected_data_shape)
+            )
+            raise AssertionError(error_msg)
+
+    def _check_fn(self, obtained_filename, expected_filename):
+        """
+        Check if dict contents dumped to a file match the contents in expected file.
+
+        :param str obtained_filename:
+        :param str expected_filename:
+        """
+        try:
+            import numpy as np
+        except ModuleNotFoundError:
+            raise ModuleNotFoundError(import_error_message("Numpy"))
+        try:
+            import pandas as pd
+        except ModuleNotFoundError:
+            raise ModuleNotFoundError(import_error_message("Pandas"))
+
+        __tracebackhide__ = True
+
+        obtained_data = pd.read_csv(str(obtained_filename))
+        expected_data = pd.read_csv(str(expected_filename))
+
+        comparison_tables_dict = {}
+        for k in obtained_data.keys():
+            obtained_column = obtained_data[k]
+            expected_column = expected_data.get(k)
+
+            if expected_column is None:
+                error_msg = f"Could not find key '{k}' in the expected results.\n"
+                error_msg += "Keys in the obtained data table: ["
+                for k in obtained_data.keys():
+                    error_msg += f"'{k}', "
+                error_msg += "]\n"
+                error_msg += "Keys in the expected data table: ["
+                for k in expected_data.keys():
+                    error_msg += f"'{k}', "
+                error_msg += "]\n"
+                error_msg += "To update values, use --force-regen option.\n\n"
+                raise AssertionError(error_msg)
+
+            tolerance_args = self._tolerances_dict.get(k, self._default_tolerance)
+
+            self._check_data_types(k, obtained_column, expected_column)
+            self._check_data_shapes(obtained_column, expected_column)
+
+            data_type = obtained_column.values.dtype
+            if data_type in [float, np.float, np.float16, np.float32, np.float64]:
+                not_close_mask = ~np.isclose(
+                    obtained_column.values,
+                    expected_column.values,
+                    equal_nan=True,
+                    **tolerance_args,
+                )
+            else:
+                not_close_mask = obtained_column.values != expected_column.values
+
+            if np.any(not_close_mask):
+                diff_ids = np.where(not_close_mask)[0]
+                diff_obtained_data = obtained_column[diff_ids]
+                diff_expected_data = expected_column[diff_ids]
+                if data_type == np.bool:
+                    diffs = np.logical_xor(obtained_column, expected_column)[diff_ids]
+                else:
+                    diffs = np.abs(obtained_column - expected_column)[diff_ids]
+
+                comparison_table = pd.concat(
+                    [diff_obtained_data, diff_expected_data, diffs], axis=1
+                )
+                comparison_table.columns = [f"obtained_{k}", f"expected_{k}", "diff"]
+                comparison_tables_dict[k] = comparison_table
+
+        if len(comparison_tables_dict) > 0:
+            error_msg = "Values are not sufficiently close.\n"
+            error_msg += "To update values, use --force-regen option.\n\n"
+            for k, comparison_table in comparison_tables_dict.items():
+                error_msg += f"{k}:\n{comparison_table}\n\n"
+            raise AssertionError(error_msg)
+
+    def _dump_fn(self, data_object, filename):
+        """
+        Dump dict contents to the given filename
+
+        :param pd.DataFrame data_object:
+        :param str filename:
+        """
+        data_object.to_csv(
+            str(filename),
+            float_format=f"%.{DataFrameRegressionFixture.DISPLAY_PRECISION}g",
+        )
+
+    def check(
+        self,
+        data_frame,
+        basename=None,
+        fullpath=None,
+        tolerances=None,
+        default_tolerance=None,
+    ):
+        """
+        Checks the given pandas dataframe against a previously recorded version, or generate a new file.
+
+        Example::
+
+            data_frame = pandas.DataFrame.from_dict({
+                'U_gas': U[0][positions],
+                'U_liquid': U[1][positions],
+                'gas_vol_frac [-]': vol_frac[0][positions],
+                'liquid_vol_frac [-]': vol_frac[1][positions],
+                'P': Pa_to_bar(P)[positions],
+            })
+            dataframe_regression.check(data_frame)
+
+        :param pandas.DataFrame data_frame: pandas DataFrame containing data for regression check.
+
+        :param str basename: basename of the file to test/record. If not given the name
+            of the test is used.
+
+        :param str fullpath: complete path to use as a reference file. This option
+            will ignore embed_data completely, being useful if a reference file is located
+            in the session data dir for example.
+
+        :param dict tolerances: dict mapping keys from the data_dict to tolerance settings for the
+            given data. Example::
+
+                tolerances={'U': Tolerance(atol=1e-2)}
+
+        :param dict default_tolerance: dict mapping the default tolerance for the current check
+            call. Example::
+
+                default_tolerance=dict(atol=1e-7, rtol=1e-18).
+
+            If not provided, will use defaults from numpy's ``isclose`` function.
+
+        ``basename`` and ``fullpath`` are exclusive.
+        """
+        try:
+            import pandas as pd
+        except ModuleNotFoundError:
+            raise ModuleNotFoundError(import_error_message("Pandas"))
+
+        import functools
+
+        __tracebackhide__ = True
+
+        assert type(data_frame) is pd.DataFrame, (
+            "Only pandas DataFrames are supported on on dataframe_regression fixture.\n"
+            "Object with type '%s' was given." % (str(type(data_frame)),)
+        )
+
+        for column in data_frame.columns:
+            array = data_frame[column]
+            # Skip assertion if an array of strings
+            if (array.dtype == "O") and (type(array[0]) is str):
+                continue
+            # Rejected: timedelta, datetime, objects, zero-terminated bytes, unicode strings and raw data
+            assert array.dtype not in ["m", "M", "O", "S", "a", "U", "V"], (
+                "Only numeric data is supported on dataframe_regression fixture.\n"
+                "Array with type '%s' was given.\n" % (str(array.dtype),)
+            )
+
+        if tolerances is None:
+            tolerances = {}
+        self._tolerances_dict = tolerances
+
+        if default_tolerance is None:
+            default_tolerance = {}
+        self._default_tolerance = default_tolerance
+
+        dump_fn = functools.partial(self._dump_fn, data_frame)
+
+        with pd.option_context(*self._pandas_display_options):
+            perform_regression_check(
+                datadir=self.datadir,
+                original_datadir=self.original_datadir,
+                request=self.request,
+                check_fn=self._check_fn,
+                dump_fn=dump_fn,
+                extension=".csv",
+                basename=basename,
+                fullpath=fullpath,
+                force_regen=self._force_regen,
+            )