Fixed #25920 -- Added support for non-uniform NUMBER_GROUPING.

django/utils/numberformat.py

@@ -15,12 +15,15 @@ def format(number, decimal_sep, decimal_pos=None, grouping=0, thousand_sep='',
 
     * decimal_sep: Decimal separator symbol (for example ".")
     * decimal_pos: Number of decimal positions
-    * grouping: Number of digits in every group limited by thousand separator
+    * grouping: Number of digits in every group limited by thousand separator.
+        For non-uniform digit grouping, it can be a sequence with the number
+        of digit group sizes following the format used by the Python locale
+        module in locale.localeconv() LC_NUMERIC grouping (e.g. (3, 2, 0)).
     * thousand_sep: Thousand separator symbol (for example ",")
     """
     use_grouping = settings.USE_L10N and settings.USE_THOUSAND_SEPARATOR
     use_grouping = use_grouping or force_grouping
-    use_grouping = use_grouping and grouping > 0
+    use_grouping = use_grouping and grouping != 0
     # Make the common case fast
     if isinstance(number, int) and not use_grouping and not decimal_pos:
         return mark_safe(six.text_type(number))
@@ -46,10 +49,22 @@ def format(number, decimal_sep, decimal_pos=None, grouping=0, thousand_sep='',
         dec_part = decimal_sep + dec_part
     # grouping
     if use_grouping:
+        try:
+            # if grouping is a sequence
+            intervals = list(grouping)
+        except TypeError:
+            # grouping is a single value
+            intervals = [grouping, 0]
+        active_interval = intervals.pop(0)
         int_part_gd = ''
-        for cnt, digit in enumerate(int_part[::-1]):
-            if cnt and not cnt % grouping:
+        cnt = 0
+        for digit in int_part[::-1]:
+            if cnt and cnt == active_interval:
+                if intervals:
+                    active_interval = intervals.pop(0) or active_interval
                 int_part_gd += thousand_sep[::-1]
+                cnt = 0
             int_part_gd += digit
+            cnt += 1
         int_part = int_part_gd[::-1]
     return sign + int_part + dec_part

docs/ref/settings.txt

@@ -1943,12 +1943,28 @@ no grouping will be applied to the number. If this setting is greater than
 ``0``, then :setting:`THOUSAND_SEPARATOR` will be used as the separator between
 those groups.
 
+Some locales use non-uniform digit grouping, e.g. ``10,00,00,000`` in
+``en_IN``. For this case, you can provide a sequence with the number of digit
+group sizes to be applied. The first number defines the size of the group
+preceding the decimal delimiter, and each number that follows defines the size
+of preceding groups. If the sequence is terminated with ``-1``, no further
+grouping is performed. If the sequence terminates with a ``0``, the last group
+size is used for the remainder of the number.
+
+Example tuple for ``en_IN``::
+
+    NUMBER_GROUPING = (3, 2, 0)
+
 Note that if :setting:`USE_L10N` is set to ``True``, then the locale-dictated
 format has higher precedence and will be applied instead.
 
 See also :setting:`DECIMAL_SEPARATOR`, :setting:`THOUSAND_SEPARATOR` and
 :setting:`USE_THOUSAND_SEPARATOR`.
 
+.. versionchanged:: 1.11
+
+    Support for non-uniform digit grouping was added.
+
 .. setting:: PREPEND_WWW
 
 ``PREPEND_WWW``

docs/releases/1.11.txt

@@ -166,7 +166,8 @@ Generic Views
 Internationalization
 ~~~~~~~~~~~~~~~~~~~~
 
-* ...
+* Number formatting and the :setting:`NUMBER_GROUPING` setting support
+  non-uniform digit grouping.
 
 Management Commands
 ~~~~~~~~~~~~~~~~~~~

tests/i18n/tests.py

@@ -576,6 +576,18 @@ class FormattingTests(SimpleTestCase):
             self.assertEqual('-66666.6', nformat(-66666.666, decimal_sep='.', decimal_pos=1))
             self.assertEqual('-66666.0', nformat(int('-66666'), decimal_sep='.', decimal_pos=1))
             self.assertEqual('10000.0', nformat(self.l, decimal_sep='.', decimal_pos=1))
+            self.assertEqual(
+                '10,00,00,000.00',
+                nformat(100000000.00, decimal_sep='.', decimal_pos=2, grouping=(3, 2, 0), thousand_sep=',')
+            )
+            self.assertEqual(
+                '1,0,00,000,0000.00',
+                nformat(10000000000.00, decimal_sep='.', decimal_pos=2, grouping=(4, 3, 2, 1, 0), thousand_sep=',')
+            )
+            self.assertEqual(
+                '10000,00,000.00',
+                nformat(1000000000.00, decimal_sep='.', decimal_pos=2, grouping=(3, 2, -1), thousand_sep=',')
+            )
             # This unusual grouping/force_grouping combination may be triggered by the intcomma filter (#17414)
             self.assertEqual('10000', nformat(self.l, decimal_sep='.', decimal_pos=0, grouping=0, force_grouping=True))