Changeset 15476

Timestamp:

27 Jun 2019, 06:07:52 (5 years ago)

Author:

Henrik Bettermann

Message:

Use decimal.Decimal to counteract Python floating point limitation.

Location:

main/waeup.kofa/trunk

Files:

• CHANGES.txt (modified) (1 diff)
• src/waeup/kofa/utils/tests/test_utils.py (modified) (1 diff)
• src/waeup/kofa/utils/utils.py (modified) (2 diffs)

main/waeup.kofa/trunk/CHANGES.txt

@@ -4 +4 @@
 1.6.1.dev0 (unreleased)
 =======================
+
+* Use decimal.Decimal to counteract Python floating point limitation.
 
 * Add level 0 (None) to course levels.

main/waeup.kofa/trunk/src/waeup/kofa/utils/tests/test_utils.py

@@ -123 +123 @@
         utils.SYSTEM_MAX_LOAD['virt-mem'] = -(sys.maxint)  # negative int
         assert utils.expensive_actions_allowed() == False
+
+    def test_format_float(self):
+        format_float= KofaUtils().format_float
+        # This is the floating point problem ...
+        self.assertEqual(4.6*100, 459.99999999999994)
+        # ... which is solved in format_float
+        self.assertEqual(format_float(4.6 ,1), '4.6')
+        self.assertEqual(format_float(4.6 ,2), '4.60')
+        self.assertEqual(format_float(4.6 ,3), '4.600')
+        self.assertEqual(format_float(4.6 ,4), '4.6000')

main/waeup.kofa/trunk/src/waeup/kofa/utils/utils.py

@@ -22 +22 @@
 import string
 import pytz
+import decimal
 from copy import deepcopy
 from random import SystemRandom as r
@@ -417 +418 @@
 
     def format_float(self, value, prec):
+        # >>> 4.6 * 100
+        # 459.99999999999994
+        value = decimal.Decimal(str(value))
         # cut floating point value
         value = int(pow(10, prec)*value) / (1.0*pow(10, prec))