_adjust_datetime: simplify calculation of base_datetime.

_adjust_datetime is called by _arrange_fields, which is called by
rdrecord, in order to calculate the base date and time, given that a
subset of the record has been selected (using sampfrom).

Previously, this function would calculate base_datetime by combining
base_date and base_time; this is now unnecessary because base_datetime
is set implicitly when base_date and base_time are set.  Likewise, it
is unnecessary to set base_time and base_date afterwards, because
these are set implicitly when base_datetime is set.

Author: Benjamin Moody

wfdb/io/record.py

@@ -565,12 +565,7 @@ def _adjust_datetime(self, sampfrom):
         if sampfrom:
             dt_seconds = sampfrom / self.fs
             if self.base_date and self.base_time:
-                self.base_datetime = datetime.datetime.combine(
-                    self.base_date, self.base_time
-                )
                 self.base_datetime += datetime.timedelta(seconds=dt_seconds)
-                self.base_date = self.base_datetime.date()
-                self.base_time = self.base_datetime.time()
             # We can calculate the time even if there is no date
             elif self.base_time:
                 tmp_datetime = datetime.datetime.combine(