sas7bdat: Check if the SAS file has zero variables

If the given SAS file has 0 rows, throw an error for the EmptyData file.
When reading, check that the column information is available. If not,
throw an error.

Author: AbdealiLoKo

doc/source/whatsnew/v0.22.0.txt

@@ -90,6 +90,7 @@ Bug Fixes
 - Bug in ``pd.read_msgpack()`` with a non existent file is passed in Python 2 (:issue:`15296`)
 - Bug in ``DataFrame.groupby`` where key as tuple in a ``MultiIndex`` were interpreted as a list of keys (:issue:`17979`)
 - Bug in :func:`pd.read_csv` where a ``MultiIndex`` with duplicate columns was not being mangled appropriately (:issue:`18062`)
+- Bug in :func:`pd.read_sas` where a file with 0 variables gave an ``AttributeError`` incorrectly. Now it gives an ``EmptyDataError``
 
 Conversion
 ^^^^^^^^^^

pandas/io/sas/sas7bdat.py

@@ -17,6 +17,7 @@
 import pandas as pd
 from pandas import compat
 from pandas.io.common import get_filepath_or_buffer, BaseIterator
+from pandas.errors import EmptyDataError
 import numpy as np
 import struct
 import pandas.io.sas.sas_constants as const
@@ -594,6 +595,9 @@ def read(self, nrows=None):
         elif nrows is None:
             nrows = self.row_count
 
+        if len(self.column_types) == 0:
+            raise EmptyDataError("No columns to parse from file")
+
         if self._current_row_in_file_index >= self.row_count:
             return None
 

pandas/tests/io/sas/data/zero_variables.sas7bdat

@@ -1,9 +1,11 @@
 import pandas as pd
 from pandas.compat import PY2
 import pandas.util.testing as tm
+from pandas.errors import EmptyDataError
 import os
 import io
 import numpy as np
+import pytest
 
 
 class TestSAS7BDAT(object):
@@ -174,3 +176,11 @@ def test_date_time():
     df0 = pd.read_csv(fname, parse_dates=['Date1', 'Date2', 'DateTime',
                                           'DateTimeHi', 'Taiw'])
     tm.assert_frame_equal(df, df0)
+
+
+def test_zero_variables():
+    # Check if the SAS file has zero variables (PR #18184)
+    dirpath = tm.get_data_path()
+    fname = os.path.join(dirpath, "zero_variables.sas7bdat")
+    with pytest.raises(EmptyDataError):
+        pd.read_sas(fname)