Add Timestamp conversion to float and unix seconds float

sem-ver: feature

Author: Philip de Nier

mediatimestamp/immutable/timestamp.py

@@ -405,6 +405,11 @@ def to_tai_sec_nsec(self) -> str:
     def to_tai_sec_frac(self, fixed_size: bool = False) -> str:
         return self.to_sec_frac(fixed_size=fixed_size)
 
+    def to_float(self) -> float:
+        """ Convert to a floating point number of seconds
+        """
+        return self._value / Timestamp.MAX_NANOSEC
+
     def to_datetime(self) -> datetime:
         sec, nsec, leap = self.to_unix()
         microsecond = int(round(nsec/1000))
@@ -437,6 +442,15 @@ def to_utc(self) -> Tuple[int, int, bool]:
         """
         return self.to_unix()
 
+    def to_unix_float(self) -> float:
+        """ Convert to unix seconds since the epoch as a floating point number
+        """
+        if self._value < 0:
+            return self.to_float()
+        else:
+            (sec, ns, _) = self.to_unix()
+            return sec + ns / Timestamp.MAX_NANOSEC
+
     def to_iso8601_utc(self) -> str:
         """ Get printed representation in ISO8601 format (UTC)
         YYYY-MM-DDThh:mm:ss.s

tests/test_timestamp.py

@@ -277,6 +277,22 @@ def test_from_float(self):
                 self.assertEqual(r, case[1],
                                  msg="Timestamp.from_float{!r} == {!r}, expected {!r}".format(case[0], r, case[1]))
 
+    def test_to_float(self):
+        """This tests that timestamps can be created from a float."""
+        cases = [
+            ((float(1.0)), Timestamp(1, 0)),
+            ((float(1_000_000_000)), Timestamp(1_000_000_000, 0)),
+            ((float(2.76)), Timestamp(2, 760_000_000)),
+            ((float(-3.14)), Timestamp(3, 140_000_000, -1)),
+            ((float(0.02)), Timestamp(0, 20_000_000))
+        ]
+
+        for case in cases:
+            with self.subTest(case=case):
+                r = case[1].to_float()
+                self.assertEqual(r, case[1],
+                                 msg="{!r},to_float() == {!r}, expected {!r}".format(case[1], r, case[0]))
+
     def test_set_value(self):
         """This tests that timestamps cannot have their value set."""
         tests_ts = [
@@ -879,3 +895,23 @@ def test_get_leap_seconds(self):
 
         for t in tests:
             self.assertEqual(t[0].get_leap_seconds(), t[1])
+
+    def test_to_unix(self):
+        tests = [
+            (Timestamp(63072008, 999999999), (63072008, 999999999, False)),  # 0 leap seconds
+            (Timestamp(63072009, 0), (63071999, 0, True)),  # 10 leap seconds at leap
+            (Timestamp(1512491629, 0), (1512491592, 0, False)),  # 37 leap seconds
+        ]
+
+        for t in tests:
+            self.assertEqual(t[0].to_unix(), t[1])
+
+    def test_to_unix_float(self):
+        tests = [
+            (Timestamp(63072008, 999999999), 63072008 + 999999999 / 1000000000),
+            (Timestamp(63072009, 0), 63071999),
+            (Timestamp(1000, 0, -1), -1000)
+        ]
+
+        for t in tests:
+            self.assertEqual(t[0].to_unix_float(), t[1])