feat: configurable rounding methods

frappe/core/doctype/system_settings/system_settings.json

@@ -17,10 +17,11 @@
   "date_format",
   "time_format",
   "number_format",
+  "first_day_of_the_week",
   "column_break_7",
   "float_precision",
   "currency_precision",
-  "first_day_of_the_week",
+  "rounding_method",
   "sec_backup_limit",
   "backup_limit",
   "encrypt_backup",
@@ -520,12 +521,19 @@
    "fieldname": "login_with_email_link_expiry",
    "fieldtype": "Int",
    "label": "Login with email link expiry (in minutes)"
+  },
+  {
+   "default": "Bankers Rounding",
+   "fieldname": "rounding_method",
+   "fieldtype": "Select",
+   "label": "Rounding Method",
+   "options": "Bankers Rounding\nRounding half away from zero"
   }
  ],
  "icon": "fa fa-cog",
  "issingle": 1,
  "links": [],
- "modified": "2022-12-20 21:45:37.651668",
+ "modified": "2023-03-06 11:31:19.144956",
  "modified_by": "Administrator",
  "module": "Core",
  "name": "System Settings",

frappe/tests/test_utils.py

@@ -6,25 +6,28 @@ import json
 import os
 import sys
 from datetime import date, datetime, time, timedelta
-from decimal import Decimal
+from decimal import ROUND_HALF_UP, Decimal, localcontext
 from enum import Enum
 from io import StringIO
 from mimetypes import guess_type
 from unittest.mock import patch
 
 import pytz
+from hypothesis import given
+from hypothesis import strategies as st
 from PIL import Image
 
 import frappe
 from frappe.installer import parse_app_name
 from frappe.model.document import Document
-from frappe.tests.utils import FrappeTestCase
+from frappe.tests.utils import FrappeTestCase, change_settings
 from frappe.utils import (
 	ceil,
 	dict_to_str,
 	evaluate_filters,
 	execute_in_shell,
 	floor,
+	flt,
 	format_timedelta,
 	get_bench_path,
 	get_file_timestamp,
@@ -1001,3 +1004,45 @@ class TestTBSanitization(FrappeTestCase):
 			self.assertIn("********", traceback)
 			self.assertIn("password =", traceback)
 			self.assertIn("safe_value", traceback)
+
+
+class TestRounding(FrappeTestCase):
+	@change_settings("System Settings", {"rounding_method": "Rounding half away from zero"})
+	def test_normal_rounding(self):
+		self.assertEqual(flt("what"), 0)
+
+		self.assertEqual(flt("0.5", 0), 1)
+		self.assertEqual(flt("0.3"), 0.3)
+
+		self.assertEqual(flt("1.5", 0), 2)
+
+		# positive rounding to integers
+		self.assertEqual(flt(0.4, 0), 0)
+		self.assertEqual(flt(0.5, 0), 1)
+		self.assertEqual(flt(1.455, 0), 1)
+		self.assertEqual(flt(1.5, 0), 2)
+
+		# negative rounding to integers
+		self.assertEqual(flt(-0.5, 0), -1)
+		self.assertEqual(flt(-1.5, 0), -2)
+
+		# negative precision i.e. round to nearest 10th
+		self.assertEqual(flt(123, -1), 120)
+		self.assertEqual(flt(125, -1), 130)
+		self.assertEqual(flt(134.45, -1), 130)
+		self.assertEqual(flt(135, -1), 140)
+
+		# # positive multiple digit rounding
+		self.assertEqual(flt(1.25, 1), 1.3)
+		self.assertEqual(flt(0.15, 1), 0.2)
+
+		# # negative multiple digit rounding
+		self.assertEqual(flt(-1.25, 1), -1.3)
+		self.assertEqual(flt(-0.15, 1), -0.2)
+
+	@change_settings("System Settings", {"rounding_method": "Rounding half away from zero"})
+	@given(st.decimals(min_value=-1e8, max_value=1e8), st.integers(min_value=-2, max_value=4))
+	def test_normal_rounding_property(self, number, precision):
+		with localcontext() as ctx:
+			ctx.rounding = ROUND_HALF_UP
+			self.assertEqual(Decimal(str(flt(float(number), precision))), round(number, precision))

frappe/utils/data.py

@@ -1047,25 +1047,36 @@ def sbool(x: str) -> bool | Any:
 
 
 def rounded(num, precision=0):
-	"""round method for round halfs to nearest even algorithm aka banker's rounding - compatible with python3"""
+	"""Round according to method set in system setting, defaults to banker's rounding"""
 	precision = cint(precision)
-	multiplier = 10**precision
 
-	# avoid rounding errors
-	num = round(num * multiplier if precision else num, 8)
+	rounding_method = frappe.get_system_settings("rounding_method") or "Bankers Rounding"
 
-	floor_num = math.floor(num)
-	decimal_part = num - floor_num
+	if rounding_method == "Bankers Rounding":
+		# avoid rounding errors
+		multiplier = 10**precision
+		num = round(num * multiplier if precision else num, 8)
 
-	if not precision and decimal_part == 0.5:
-		num = floor_num if (floor_num % 2 == 0) else floor_num + 1
-	else:
-		if decimal_part == 0.5:
-			num = floor_num + 1
+		floor_num = math.floor(num)
+		decimal_part = num - floor_num
+
+		if not precision and decimal_part == 0.5:
+			num = floor_num if (floor_num % 2 == 0) else floor_num + 1
 		else:
-			num = round(num)
+			if decimal_part == 0.5:
+				num = floor_num + 1
+			else:
+				num = round(num)
 
-	return (num / multiplier) if precision else num
+		return (num / multiplier) if precision else num
+
+	elif rounding_method == "Rounding half away from zero":
+		if num == 0:
+			return 0.0
+		# Epsilon is small correctional value added to correctly round numbers which can't be
+		# represented in IEEE 754 representation.
+		epsilon = 2.0 ** (math.log(abs(num), 2) - 52.0)
+		return round(num + math.copysign(epsilon, num), precision)
 
 
 def remainder(numerator: NumericType, denominator: NumericType, precision: int = 2) -> NumericType:

pyproject.toml

@@ -102,3 +102,4 @@ Faker = "~=13.12.1"
 pyngrok = "~=5.0.5"
 unittest-xml-reporting = "~=3.0.4"
 watchdog = "~=2.1.9"
+hypothesis = "~=6.68.2"