Cleanup and add comments

pandas-dev · jreback · Jul 30, 2018 · Jul 7, 2018 · Jul 8, 2018 · Jul 8, 2018
commit f89d6b6b02a0e750124430720bcab1509cf05bd5
diff --git a/pandas/_libs/tslib.pyx b/pandas/_libs/tslib.pyx
@@ -456,14 +456,15 @@ cpdef array_to_datetime(ndarray[object] values, errors='raise',
            is encountered
 
     Also returns a pytz.FixedOffset if an array of strings with the same
-    timezone offset if passed and utc=True is not passed
+    timezone offset is passed and utc=True is not passed. Otherwise, None
+    is returned
 
     Handles datetime.date, datetime.datetime, np.datetime64 objects, numeric,
     strings
 
     Returns
     -------
-    (ndarray, timezone offset)
+    tuple (ndarray, timezone offset)
     """
     cdef:
         Py_ssize_t i, n = len(values)
@@ -481,18 +482,12 @@ cpdef array_to_datetime(ndarray[object] values, errors='raise',
         bint is_coerce = errors=='coerce'
         _TSObject _ts
         int out_local=0, out_tzoffset=0
-        # Can't directly create a ndarray[int] out_local,
-        # since most np.array constructors expect a long dtype
-        # while _string_to_dts expects purely int
-        # maybe something I am missing?
-        ndarray[int64_t] out_local_values
         ndarray[int64_t] out_tzoffset_vals
 
     # specify error conditions
     assert is_raise or is_ignore or is_coerce
 
     try:
-        out_local_values = np.empty(n, dtype=np.int64)
         out_tzoffset_vals = np.empty(n, dtype=np.int64)
         result = np.empty(n, dtype='M8[ns]')
         iresult = result.view('i8')
@@ -630,7 +625,6 @@ cpdef array_to_datetime(ndarray[object] values, errors='raise',
                     # No error raised by string_to_dts, pick back up
                     # where we left off
                     out_tzoffset_vals[i] = out_tzoffset
-                    out_local_values[i] = out_local
                     value = dtstruct_to_dt64(&dts)
                     if out_local == 1:
                         seen_datetime_offset = 1
@@ -685,12 +679,12 @@ cpdef array_to_datetime(ndarray[object] values, errors='raise',
             #    object path where an array of datetimes
             #    (with individual datutil.tzoffsets) are returned
 
-            # Faster to compare integers than to compare objects
+            # Faster to compare integers than to compare pytz objects
             is_same_offsets = (out_tzoffset_vals[0] == out_tzoffset_vals).all()
             if not is_same_offsets:
                 raise TypeError
             else:
-                tz_out = pytz.FixedOffset(out_tzoffset_vals[0])
+                tz_out = pytz.FixedOffset(out_tzoffset)
 
         return result, tz_out
     except OutOfBoundsDatetime:

diff --git a/pandas/core/tools/datetimes.py b/pandas/core/tools/datetimes.py
@@ -412,7 +412,7 @@ def to_datetime(arg, errors='raise', dayfirst=False, yearfirst=False,
         datetime.datetime objects as well).
     box : boolean, default True
 
-        - If True returns a DatetimeIndex or Index
+        - If True returns a DatetimeIndex or Index-like object
         - If False returns ndarray of values.
     format : string, default None
         strftime to parse time, eg "%d/%m/%Y", note that "%f" will parse

diff --git a/pandas/tests/indexes/datetimes/test_tools.py b/pandas/tests/indexes/datetimes/test_tools.py
@@ -580,7 +580,7 @@ def test_week_without_day_and_calendar_year(self, date, format):
         with tm.assert_raises_regex(ValueError, msg):
             pd.to_datetime(date, format=format)
 
-    def test_ts_strings_with_same_offset(self):
+    def test_iso_8601_strings_with_same_offset(self):
         # GH 17697, 11736
         ts_str = "2015-11-18 15:30:00+05:30"
         result = to_datetime(ts_str)
@@ -594,7 +594,7 @@ def test_ts_strings_with_same_offset(self):
         result = DatetimeIndex([ts_str] * 2)
         tm.assert_index_equal(result, expected)
 
-    def test_ts_strings_with_different_offsets(self):
+    def test_iso_8601_strings_with_different_offsets(self):
         # GH 17697, 11736
         ts_strings = ["2015-11-18 15:30:00+05:30",
                       "2015-11-18 16:30:00+06:30"]

diff --git a/pandas/tests/tslibs/test_array_to_datetime.py b/pandas/tests/tslibs/test_array_to_datetime.py
@@ -78,9 +78,8 @@ def test_parsing_timezone_offsets(self, dt_string, expected_tz):
         # All of these datetime strings with offsets are equivalent
         # to the same datetime after the timezone offset is added
 
-        # TODO: Appears that parsing non-ISO strings adjust the date to UTC
-        # but don't return the offset. Not sure if this is the intended
-        # behavior of non-iso strings in np_datetime_strings
+        # Non-ISO 8601 datetime strings will not return a timezone offset
+        # as a limitation of the C parser
         arr = np.array(['01-01-2013 00:00:00'], dtype=object)
         expected = tslib.array_to_datetime(arr)[0]