cleanup, simplification, better error message

Author: jbrockmendel

pandas/core/arrays/datetimes.py

@@ -1698,9 +1698,13 @@ def _generate_regular_range(cls, start, end, periods, freq):
             e = _generate_range_overflow_safe(b, periods, stride, side='start')
             tz = start.tz
         elif end is not None:
-            e = Timestamp(end).value + stride
+            e = Timestamp(end).value
             b = _generate_range_overflow_safe(e, periods, stride, side='end')
             tz = end.tz
+
+            # add an additional step to `e` because np.arange(b, e) will
+            #  not include `e`
+            e += stride
         else:
             raise ValueError("at least 'start' or 'end' should be specified "
                              "if a 'period' is given.")
@@ -1752,7 +1756,7 @@ def _generate_range_overflow_safe(endpoint, periods, stride,
     i64max = np.iinfo(np.int64).max
     msg = ('Cannot generate range with {side}={endpoint} and '
            'periods={periods}'
-           .format(side=side, endpoint=endpoint, periods=periods))
+           .format(side=side, endpoint=Timestamp(endpoint), periods=periods))
 
     with np.errstate(over="raise"):
         # if periods * strides cannot be multiplied within the *uint64* bounds,
@@ -1772,12 +1776,6 @@ def _generate_range_overflow_safe(endpoint, periods, stride,
         # no chance of not-overflowing
         raise tslib.OutOfBoundsDatetime(msg)
 
-    elif (side == 'end' and endpoint > i64max and endpoint - stride <= i64max):
-        # in _generate_regular_range we added `stride` thereby overflowing
-        #  the bounds.  Adjust to fix this.
-        return _generate_range_overflow_safe(endpoint - stride,
-                                             periods - 1, stride, side)
-
     # split into smaller pieces
     return _generate_range_recurse(endpoint, periods, stride, side)
 
@@ -1849,7 +1847,6 @@ def _generate_range_recurse(endpoint, periods, stride, side):
     mid_periods = periods // 2
     remaining = periods - mid_periods
     assert 0 < remaining < periods, (remaining, periods, endpoint, stride)
-    print(periods, mid_periods, endpoint, stride, side)
 
     midpoint = _generate_range_overflow_safe(endpoint, mid_periods,
                                              stride, side)