DEPR: Deprecate from_csv in favor of read_csv (pandas-dev#17812)

Closes pandas-devgh-4191.

Author: gfyoung

doc/source/whatsnew/v0.21.0.txt

@@ -715,6 +715,7 @@ Other API Changes
 Deprecations
 ~~~~~~~~~~~~
 
+- :meth:`DataFrame.from_csv` and :meth:`Series.from_csv` have been deprecated in favor of :func:`read_csv()` (:issue:`4191`)
 - :func:`read_excel()` has deprecated ``sheetname`` in favor of ``sheet_name`` for consistency with ``.to_excel()`` (:issue:`10559`).
 - :func:`read_excel()` has deprecated ``parse_cols`` in favor of ``usecols`` for consistency with :func:`read_csv` (:issue:`4988`)
 - :func:`read_csv()` has deprecated the ``tupleize_cols`` argument. Column tuples will always be converted to a ``MultiIndex`` (:issue:`17060`)

pandas/core/frame.py

@@ -298,7 +298,7 @@ def _constructor(self):
 
     _constructor_sliced = Series
     _deprecations = NDFrame._deprecations | frozenset(
-        ['sortlevel', 'get_value', 'set_value'])
+        ['sortlevel', 'get_value', 'set_value', 'from_csv'])
 
     @property
     def _constructor_expanddim(self):
@@ -1291,7 +1291,7 @@ def from_csv(cls, path, header=0, sep=',', index_col=0, parse_dates=True,
                  encoding=None, tupleize_cols=False,
                  infer_datetime_format=False):
         """
-        Read CSV file (DISCOURAGED, please use :func:`pandas.read_csv`
+        Read CSV file (DEPRECATED, please use :func:`pandas.read_csv`
         instead).
 
         It is preferable to use the more powerful :func:`pandas.read_csv`
@@ -1339,6 +1339,13 @@ def from_csv(cls, path, header=0, sep=',', index_col=0, parse_dates=True,
         y : DataFrame
 
         """
+
+        warnings.warn("from_csv is deprecated. Please use read_csv(...) "
+                      "instead. Note that some of the default arguments are "
+                      "different, so please refer to the documentation "
+                      "for from_csv when changing your function calls",
+                      FutureWarning, stacklevel=2)
+
         from pandas.io.parsers import read_table
         return read_table(path, header=header, sep=sep,
                           parse_dates=parse_dates, index_col=index_col,

pandas/core/series.py

@@ -147,7 +147,7 @@ class Series(base.IndexOpsMixin, generic.NDFrame):
     _metadata = ['name']
     _accessors = frozenset(['dt', 'cat', 'str'])
     _deprecations = generic.NDFrame._deprecations | frozenset(
-        ['sortlevel', 'reshape', 'get_value', 'set_value'])
+        ['sortlevel', 'reshape', 'get_value', 'set_value', 'from_csv'])
     _allow_index_ops = True
 
     def __init__(self, data=None, index=None, dtype=None, name=None,
@@ -2688,7 +2688,7 @@ def between(self, left, right, inclusive=True):
     def from_csv(cls, path, sep=',', parse_dates=True, header=None,
                  index_col=0, encoding=None, infer_datetime_format=False):
         """
-        Read CSV file (DISCOURAGED, please use :func:`pandas.read_csv`
+        Read CSV file (DEPRECATED, please use :func:`pandas.read_csv`
         instead).
 
         It is preferable to use the more powerful :func:`pandas.read_csv`
@@ -2736,6 +2736,9 @@ def from_csv(cls, path, sep=',', parse_dates=True, header=None,
         -------
         y : Series
         """
+
+        # We're calling `DataFrame.from_csv` in the implementation,
+        # which will propagate a warning regarding `from_csv` deprecation.
         from pandas.core.frame import DataFrame
         df = DataFrame.from_csv(path, header=header, index_col=index_col,
                                 sep=sep, parse_dates=parse_dates,

pandas/tests/frame/test_to_csv.py

@@ -31,6 +31,21 @@
 
 class TestDataFrameToCSV(TestData):
 
+    def read_csv(self, path, **kwargs):
+        params = dict(index_col=0, parse_dates=True)
+        params.update(**kwargs)
+
+        return pd.read_csv(path, **params)
+
+    def test_from_csv_deprecation(self):
+        # see gh-17812
+        with ensure_clean('__tmp_from_csv_deprecation__') as path:
+            self.tsframe.to_csv(path)
+
+            with tm.assert_produces_warning(FutureWarning):
+                depr_recons = DataFrame.from_csv(path)
+                assert_frame_equal(self.tsframe, depr_recons)
+
     def test_to_csv_from_csv1(self):
 
         with ensure_clean('__tmp_to_csv_from_csv1__') as path:
@@ -43,24 +58,25 @@ def test_to_csv_from_csv1(self):
 
             # test roundtrip
             self.tsframe.to_csv(path)
-            recons = DataFrame.from_csv(path)
-
+            recons = self.read_csv(path)
             assert_frame_equal(self.tsframe, recons)
 
             self.tsframe.to_csv(path, index_label='index')
-            recons = DataFrame.from_csv(path, index_col=None)
+            recons = self.read_csv(path, index_col=None)
+
             assert(len(recons.columns) == len(self.tsframe.columns) + 1)
 
             # no index
             self.tsframe.to_csv(path, index=False)
-            recons = DataFrame.from_csv(path, index_col=None)
+            recons = self.read_csv(path, index_col=None)
             assert_almost_equal(self.tsframe.values, recons.values)
 
             # corner case
             dm = DataFrame({'s1': Series(lrange(3), lrange(3)),
                             's2': Series(lrange(2), lrange(2))})
             dm.to_csv(path)
-            recons = DataFrame.from_csv(path)
+
+            recons = self.read_csv(path)
             assert_frame_equal(dm, recons)
 
     def test_to_csv_from_csv2(self):
@@ -71,27 +87,26 @@ def test_to_csv_from_csv2(self):
             df = DataFrame(np.random.randn(3, 3), index=['a', 'a', 'b'],
                            columns=['x', 'y', 'z'])
             df.to_csv(path)
-            result = DataFrame.from_csv(path)
+            result = self.read_csv(path)
             assert_frame_equal(result, df)
 
             midx = MultiIndex.from_tuples(
                 [('A', 1, 2), ('A', 1, 2), ('B', 1, 2)])
             df = DataFrame(np.random.randn(3, 3), index=midx,
                            columns=['x', 'y', 'z'])
+
             df.to_csv(path)
-            result = DataFrame.from_csv(path, index_col=[0, 1, 2],
-                                        parse_dates=False)
-            # TODO from_csv names index ['Unnamed: 1', 'Unnamed: 2'] should it
-            # ?
+            result = self.read_csv(path, index_col=[0, 1, 2],
+                                   parse_dates=False)
             assert_frame_equal(result, df, check_names=False)
 
             # column aliases
             col_aliases = Index(['AA', 'X', 'Y', 'Z'])
             self.frame2.to_csv(path, header=col_aliases)
-            rs = DataFrame.from_csv(path)
+
+            rs = self.read_csv(path)
             xp = self.frame2.copy()
             xp.columns = col_aliases
-
             assert_frame_equal(xp, rs)
 
             pytest.raises(ValueError, self.frame2.to_csv, path,
@@ -231,8 +246,9 @@ def make_dtnat_arr(n, nnat=None):
         with ensure_clean('1.csv') as pth:
             df = DataFrame(dict(a=s1, b=s2))
             df.to_csv(pth, chunksize=chunksize)
-            recons = DataFrame.from_csv(pth)._convert(datetime=True,
-                                                      coerce=True)
+
+            recons = self.read_csv(pth)._convert(datetime=True,
+                                                 coerce=True)
             assert_frame_equal(df, recons, check_names=False,
                                check_less_precise=True)
 
@@ -247,16 +263,17 @@ def _do_test(df, r_dtype=None, c_dtype=None,
                 if rnlvl is not None:
                     kwargs['index_col'] = lrange(rnlvl)
                 kwargs['header'] = lrange(cnlvl)
+
                 with ensure_clean('__tmp_to_csv_moar__') as path:
                     df.to_csv(path, encoding='utf8',
                               chunksize=chunksize, tupleize_cols=False)
-                    recons = DataFrame.from_csv(
-                        path, tupleize_cols=False, **kwargs)
+                    recons = self.read_csv(path, tupleize_cols=False, **kwargs)
             else:
                 kwargs['header'] = 0
+
                 with ensure_clean('__tmp_to_csv_moar__') as path:
                     df.to_csv(path, encoding='utf8', chunksize=chunksize)
-                    recons = DataFrame.from_csv(path, **kwargs)
+                    recons = self.read_csv(path, **kwargs)
 
             def _to_uni(x):
                 if not isinstance(x, compat.text_type):
@@ -398,7 +415,7 @@ def test_to_csv_from_csv_w_some_infs(self):
 
         with ensure_clean() as path:
             self.frame.to_csv(path)
-            recons = DataFrame.from_csv(path)
+            recons = self.read_csv(path)
 
             # TODO to_csv drops column name
             assert_frame_equal(self.frame, recons, check_names=False)
@@ -413,7 +430,7 @@ def test_to_csv_from_csv_w_all_infs(self):
 
         with ensure_clean() as path:
             self.frame.to_csv(path)
-            recons = DataFrame.from_csv(path)
+            recons = self.read_csv(path)
 
             # TODO to_csv drops column name
             assert_frame_equal(self.frame, recons, check_names=False)
@@ -448,11 +465,13 @@ def test_to_csv_headers(self):
         to_df = DataFrame([[1, 2], [3, 4]], columns=['X', 'Y'])
         with ensure_clean('__tmp_to_csv_headers__') as path:
             from_df.to_csv(path, header=['X', 'Y'])
-            recons = DataFrame.from_csv(path)
+            recons = self.read_csv(path)
+
             assert_frame_equal(to_df, recons)
 
             from_df.to_csv(path, index=False, header=['X', 'Y'])
-            recons = DataFrame.from_csv(path)
+            recons = self.read_csv(path)
+
             recons.reset_index(inplace=True)
             assert_frame_equal(to_df, recons)
 
@@ -471,13 +490,15 @@ def test_to_csv_multiindex(self):
 
             # round trip
             frame.to_csv(path)
-            df = DataFrame.from_csv(path, index_col=[0, 1], parse_dates=False)
+
+            df = self.read_csv(path, index_col=[0, 1],
+                               parse_dates=False)
 
             # TODO to_csv drops column name
             assert_frame_equal(frame, df, check_names=False)
             assert frame.index.names == df.index.names
 
-            # needed if setUP becomes a classmethod
+            # needed if setUp becomes a class method
             self.frame.index = old_index
 
             # try multiindex with dates
@@ -487,21 +508,22 @@ def test_to_csv_multiindex(self):
             tsframe.index = MultiIndex.from_arrays(new_index)
 
             tsframe.to_csv(path, index_label=['time', 'foo'])
-            recons = DataFrame.from_csv(path, index_col=[0, 1])
+            recons = self.read_csv(path, index_col=[0, 1])
+
             # TODO to_csv drops column name
             assert_frame_equal(tsframe, recons, check_names=False)
 
             # do not load index
             tsframe.to_csv(path)
-            recons = DataFrame.from_csv(path, index_col=None)
+            recons = self.read_csv(path, index_col=None)
             assert len(recons.columns) == len(tsframe.columns) + 2
 
             # no index
             tsframe.to_csv(path, index=False)
-            recons = DataFrame.from_csv(path, index_col=None)
+            recons = self.read_csv(path, index_col=None)
             assert_almost_equal(recons.values, self.tsframe.values)
 
-            # needed if setUP becomes classmethod
+            # needed if setUp becomes class method
             self.tsframe.index = old_index
 
         with ensure_clean('__tmp_to_csv_multiindex__') as path:
@@ -606,7 +628,8 @@ def _make_frame(names=None):
         with ensure_clean('__tmp_to_csv_multiindex__') as path:
             # empty
             tsframe[:0].to_csv(path)
-            recons = DataFrame.from_csv(path)
+            recons = self.read_csv(path)
+
             exp = tsframe[:0]
             exp.index = []
 
@@ -631,7 +654,7 @@ def test_to_csv_withcommas(self):
 
         with ensure_clean('__tmp_to_csv_withcommas__.csv') as path:
             df.to_csv(path)
-            df2 = DataFrame.from_csv(path)
+            df2 = self.read_csv(path)
             assert_frame_equal(df2, df)
 
     def test_to_csv_mixed(self):
@@ -746,7 +769,7 @@ def test_to_csv_wide_frame_formatting(self):
 
     def test_to_csv_bug(self):
         f1 = StringIO('a,1.0\nb,2.0')
-        df = DataFrame.from_csv(f1, header=None)
+        df = self.read_csv(f1, header=None)
         newdf = DataFrame({'t': df[df.columns[0]]})
 
         with ensure_clean() as path: