Add information about precision on format_percent

babel/numbers.py

@@ -337,7 +337,7 @@ def format_currency(number, currency, format=None, locale=LC_NUMERIC,
     return pattern.apply(number, locale, currency=currency, force_frac=frac)
 
 
-def format_percent(number, format=None, locale=LC_NUMERIC):
+def format_percent(number, format=None, locale=LC_NUMERIC, scale=None):
     """Return formatted percent value for a specific locale.
 
     >>> format_percent(0.34, locale='en_US')
@@ -347,20 +347,44 @@ def format_percent(number, format=None, locale=LC_NUMERIC):
     >>> format_percent(25.1234, locale='sv_SE')
     u'2\\xa0512\\xa0%'
 
+    You can set the percent precision changing the scale
+    >>> format_percent(0.345, locale='en_US', scale=2)
+    u'34.50%'
+
     The format pattern can also be specified explicitly:
 
     >>> format_percent(25.1234, u'#,##0\u2030', locale='en_US')
     u'25,123\u2030'
 
+    The format pattern with percent or per mille symbol change the precision:
+
+    >>> format_percent(0.346, locale='en_US')
+    u'35%'
+
+    >>> format_percent(0.346, u'#,###.##%', locale='en_US')
+    u'34.6%'
+
+    In this case is considered the precision by format and not the param scale.
+
     :param number: the percent number to format
     :param format:
     :param locale: the `Locale` object or locale identifier
+    :param scale: the number to change the percent precision
     """
+    if scale and isinstance(scale, int):
+        frac = (scale, scale)
+    else:
+        frac = None
+
     locale = Locale.parse(locale)
     if not format:
         format = locale.percent_formats.get(format)
+    else:
+        # if the format was setted is disconsidered any scale value
+        # to use the format scale
+        frac = None
     pattern = parse_pattern(format)
-    return pattern.apply(number, locale)
+    return pattern.apply(number, locale, force_frac=frac)
 
 
 def format_scientific(number, format=None, locale=LC_NUMERIC):
@@ -617,7 +641,8 @@ def apply(self, value, locale, currency=None, force_frac=None):
             retval = retval.replace(u'¤¤¤',
                                     get_currency_name(currency, value, locale))
             retval = retval.replace(u'¤¤', currency.upper())
-            retval = retval.replace(u'¤', get_currency_symbol(currency, locale))
+            retval = retval.replace(
+                u'¤', get_currency_symbol(currency, locale))
         return retval
 
     #

tests/test_numbers.py

@@ -279,6 +279,20 @@ def test_format_percent():
             == u'2\xa0512\xa0%')
     assert (numbers.format_percent(25.1234, u'#,##0\u2030', locale='en_US')
             == u'25,123\u2030')
+    assert numbers.format_percent(0.346, locale='en_US', scale=1) == u'34.6%'
+    assert numbers.format_percent(0.346, locale='en_US', scale=2) == u'34.60%'
+    assert numbers.format_percent(0.3465, locale='en_US', scale=2) == u'34.65%'
+    # this assertion verify that the scale format is greater than
+    # the input scale
+    assert numbers.format_percent(
+        0.34654, format='#,###.##%', locale='en_US', scale=3) == u'34.65%'
+    assert numbers.format_percent(
+        0.346, format='#,###.##%', locale='en_US', scale=3) == u'34.6%'
+    # this assertion is to validate if the format_percent 
+    # is not broken if the scale input has a wrong type
+    assert numbers.format_percent(0.3465, locale='en_US', scale='a') == u'35%'
+    # validate bas percent format
+    assert numbers.format_percent(0.3465, locale='cs_CZ', scale=2) == u'34,65\xa0%'
 
 
 def test_scientific_exponent_displayed_as_integer():