Merge pull request #1 from duncanmmacleod/parse-str-decimal

Use decimal.Decimal to parse strings
gwpy · Jun 13, 2017 · ad03d2f · ad03d2f
2 parents 1248dd6 + 2260ff7
commit ad03d2f
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Showing 2 changed files with 13 additions and 8 deletions.
diff --git a/ligotimegps/__init__.py b/ligotimegps/__init__.py
@@ -19,6 +19,7 @@
 
 from math import (modf, log)
 from functools import wraps
+from decimal import Decimal
 
 try:
     from functools import total_ordering
@@ -86,17 +87,18 @@ def __init__(self, seconds, nanoseconds=0):
             nanoseconds += ns * 1e9
         elif not isinstance(seconds, six.integer_types):
             if isinstance(seconds, (six.binary_type, six.text_type)):
-                sign = -1 if seconds.lstrip().startswith("-") else +1
                 try:
-                    if "." in seconds:
-                        seconds, ns = seconds.split(".")
-                        ns = round(sign * float("." + ns) * 1e9)
-                    else:
-                        ns = 0
-                    seconds = int(seconds)
-                except:
+                    seconds = str(Decimal(seconds))
+                except ArithmeticError:
                     raise TypeError("invalid literal for LIGOTimeGPS(): %s"
                                     % seconds)
+                sign = -1 if seconds.startswith("-") else +1
+                if "." in seconds:
+                    seconds, ns = seconds.split(".")
+                    ns = sign * int(ns.ljust(9, '0'))
+                else:
+                    ns = 0
+                seconds = int(seconds)
                 nanoseconds += ns
             elif (hasattr(seconds, "gpsSeconds") and
                   hasattr(seconds, "gpsNanoSeconds")):  # lal.LIGOTimeGPS

diff --git a/ligotimegps/test_ligotimegps.py b/ligotimegps/test_ligotimegps.py
@@ -52,6 +52,9 @@ def test_creation(self):
         a = LIGOTimeGPS("1", "234")
         self.assertEqual(a.gpsSeconds, 1)
         self.assertEqual(a.gpsNanoSeconds, 234)
+        a = LIGOTimeGPS("1.2345678987654321e9")
+        self.assertEqual(a.gpsSeconds, 1234567898)
+        self.assertEqual(a.gpsNanoSeconds, 765432100)
         # check errors
         self.assertRaises(TypeError, LIGOTimeGPS, 'test')
         self.assertRaises(TypeError, LIGOTimeGPS, None)