[DataFrame] Pass read_csv kwargs to _infer_column (ray-project#1894)

* pass kwargs to _infer_column

* adding small test for non-comma delim

* fix lint

python/ray/dataframe/io.py

@@ -114,8 +114,8 @@ def _get_firstline(file_path):
     return first
 
 
-def _infer_column(first_line):
-    return pd.read_csv(BytesIO(first_line)).columns
+def _infer_column(first_line, kwargs={}):
+    return pd.read_csv(BytesIO(first_line), **kwargs).columns
 
 
 @ray.remote
@@ -247,7 +247,7 @@ def read_csv(filepath,
     offsets = _compute_offset(filepath, get_npartitions())
 
     first_line = _get_firstline(filepath)
-    columns = _infer_column(first_line)
+    columns = _infer_column(first_line, kwargs=kwargs)
 
     df_obj_ids = []
     for start, end in offsets:

python/ray/dataframe/test/test_io.py

@@ -40,15 +40,15 @@ def teardown_parquet_file():
 
 
 @pytest.fixture
-def setup_csv_file(row_size, force=False):
+def setup_csv_file(row_size, force=False, delimiter=','):
     if os.path.exists(TEST_CSV_FILENAME) and not force:
         pass
     else:
         df = pd.DataFrame({
             'col1': np.arange(row_size),
             'col2': np.arange(row_size)
         })
-        df.to_csv(TEST_CSV_FILENAME)
+        df.to_csv(TEST_CSV_FILENAME, sep=delimiter)
 
 
 @pytest.fixture
@@ -88,3 +88,14 @@ def test_from_csv():
     assert ray_df_equals_pandas(ray_df, pd_df)
 
     teardown_csv_file()
+
+
+def test_from_csv_delimiter():
+    setup_csv_file(SMALL_ROW_SIZE, delimiter='|')
+
+    pd_df = pd.read_csv(TEST_CSV_FILENAME)
+    ray_df = io.read_csv(TEST_CSV_FILENAME)
+
+    assert ray_df_equals_pandas(ray_df, pd_df)
+
+    teardown_csv_file()