add initial pandas HDF fileformat

CHANGES.md

@@ -1,6 +1,8 @@
 0.6 (unreleased)
 ----------------
 
+- Add ability to compare to Pandas DataFrames and store them as HDF5 files [#23]
+
 0.5 (2022-01-12)
 ----------------
 

README.rst

@@ -15,7 +15,8 @@ in cases where the arrays are too large to conveniently hard-code them
 in the tests (e.g. ``np.testing.assert_allclose(x, [1, 2, 3])``).
 
 The basic idea is that you can write a test that generates a Numpy array (or
-other related objects depending on the format). You can then either run the
+other related objects depending on the format, e.g. pandas DataFrame).
+You can then either run the
 tests in a mode to **generate** reference files from the arrays, or you can run
 the tests in **comparison** mode, which will compare the results of the tests to
 the reference ones within some tolerance.
@@ -25,6 +26,7 @@ At the moment, the supported file formats for the reference files are:
 -  A plain text-based format (based on Numpy ``loadtxt`` output)
 -  The FITS format (requires `astropy <http://www.astropy.org>`__). With this
    format, tests can return either a Numpy array for a FITS HDU object.
+-  A pandas HDF5 format using the pandas HDFStore
 
 For more information on how to write tests to do this, see the **Using**
 section below.

pytest_arraydiff/plugin.py

@@ -137,9 +137,43 @@ def write(filename, data, **kwargs):
         return np.savetxt(filename, data, **kwargs)
 
 
+class PDHDFDiff(BaseDiff):
+
+    extension = 'h5'
+
+    @staticmethod
+    def read(filename):
+        import pandas as pd
+        return pd.read_hdf(filename)
+
+    @staticmethod
+    def write(filename, data, **kwargs):
+        import pandas as pd
+        key = os.path.basename(filename).replace('.h5', '')
+        return data.to_hdf(filename, key, **kwargs)
+
+    @classmethod
+    def compare(cls, reference_file, test_file, atol=None, rtol=None):
+        import pandas.testing as pdt
+        import pandas as pd
+
+        ref_data = pd.read_hdf(reference_file)
+        test_data = pd.read_hdf(test_file)
+        try:
+            pdt.assert_frame_equal(ref_data, test_data)
+        except AssertionError as exc:
+            message = "\n\na: {0}".format(test_file) + '\n'
+            message += "b: {0}".format(reference_file) + '\n'
+            message += exc.args[0]
+            return False, message
+        else:
+            return True, ""
+
+
 FORMATS = {}
 FORMATS['fits'] = FITSDiff
 FORMATS['text'] = TextDiff
+FORMATS['pd_hdf'] = PDHDFDiff
 
 
 def _download_file(url):

setup.cfg

@@ -36,6 +36,8 @@ install_requires =
 [options.extras_require]
 test =
     astropy
+    pandas
+    tables
 
 [options.entry_points]
 pytest11 =

tests/test_pytest_arraydiff.py

@@ -18,6 +18,13 @@ def test_succeeds_func_text():
     return np.arange(3 * 5).reshape((3, 5))
 
 
+@pytest.mark.array_compare(file_format='pd_hdf', reference_dir=reference_dir)
+def test_succeeds_func_pdhdf():
+    pd = pytest.importorskip('pandas')
+    return pd.DataFrame(data=np.arange(20, dtype='int64'),
+                        columns=['test_data'])
+
+
 @pytest.mark.array_compare(file_format='fits', reference_dir=reference_dir)
 def test_succeeds_func_fits():
     return np.arange(3 * 5).reshape((3, 5)).astype(np.int64)