Accept Micro symbol as input prefix

README.rst

@@ -226,6 +226,12 @@ SI (Decimal) Prefixes
 |   q    | Quecto | |10^-30| |
 +--------+--------+----------+
 
+.. note::
+  Prefixed uses the lower case Greek letter mu ('μ'), U+03BC, to represent the Micro
+  prefix, but will accept input using the Micro sign ('µ'), U+00B5. This complies
+  with the preference defined in `Unicode Technical Report #25`_ section 2.5.
+
+
 IEC (Binary) Prefixes
 ^^^^^^^^^^^^^^^^^^^^^
 
@@ -249,6 +255,7 @@ IEC (Binary) Prefixes
 |   K    | Kibi | |2^10| |
 +--------+------+--------+
 
+.. _Unicode Technical Report #25: https://www.unicode.org/reports/tr25
 .. _SI (decimal): https://en.wikipedia.org/wiki/Metric_prefix
 .. _IEC (binary): https://en.wikipedia.org/wiki/Binary_prefix
 .. _float: https://docs.python.org/3/library/functions.html#float

doc/prefixes.rst

@@ -57,6 +57,12 @@ SI (Decimal) Prefixes
 |   q    | Quecto | |10^-30| |
 +--------+--------+----------+
 
+.. note::
+  Prefixed uses the lower case Greek letter mu ('μ'), U+03BC, to represent the Micro
+  prefix, but will accept input using the Micro sign ('µ'), U+00B5. This complies
+  with the preference defined in `Unicode Technical Report #25`_ section 2.5.
+
+
 IEC (Binary) Prefixes
 ^^^^^^^^^^^^^^^^^^^^^
 
@@ -80,6 +86,8 @@ IEC (Binary) Prefixes
 |   K    | Kibi | |2^10| |
 +--------+------+--------+
 
+.. _Unicode Technical Report #25: https://www.unicode.org/reports/tr25
+
 .. |10^30| replace:: 10\ :sup:`30`\
 .. |10^27| replace:: 10\ :sup:`27`\
 .. |10^24| replace:: 10\ :sup:`24`\

doc/spelling_wordlist.txt

@@ -1,4 +1,5 @@
 μ
+µ
 Atto
 Exa
 Exbi

prefixed/__init__.py

@@ -46,8 +46,13 @@
     # spec_type: Single non-numeric character
     r'(?P<type>\D)?$'
 )
+
+# pylint: disable-next=wrong-spelling-in-comment
+# \xce\xbc and \xc2\xb5 included for micro for Python 2.7 strings
+# Support for both Greek letter mu and legacy micro symbol
 RE_PREFIX = re.compile(
-    r'(?P<value>[-+]?\d+\.?(?:\d+)?(?:[eE]?\d)?) ?(?P<prefix>(?:[a-zA-Z\u03bc]|\xce\xbc)i?)$'
+    r'(?P<value>[-+]?\d+\.?(?:\d+)?(?:[eE]?\d)?) ?'
+    r'(?P<prefix>(?:[a-zA-Z\u03bc\u00B5]|\xce\xbc|\xc2\xb5)i?)$'
 )
 
 SI_SMALL = {
@@ -272,6 +277,8 @@ def __new__(cls, value=0.0):
                 prefix = match.group('prefix')
                 if prefix[-1] == 'i':
                     magnitude = IEC_MAGNITUDE.get(prefix[0])
+                elif prefix in {'µ', u'µ'}:  # pylint: disable=duplicate-value  # Python 2.7
+                    magnitude = SI_MAGNITUDE.get('μ')
                 else:
                     magnitude = SI_MAGNITUDE.get(prefix)
 

tests/test_float.py

@@ -39,8 +39,7 @@ def test_str(self):
         self.assertEqual(str(Float(1.0)), '1.0')
 
 
-# pylint: disable=expression-not-assigned
-class TestFloatFormatting(unittest.TestCase):
+class TestFloatFormatting(unittest.TestCase):  # pylint: disable=too-many-public-methods
     """
     Tests for prefixed.Float input and output
     """
@@ -261,7 +260,7 @@ def test_input_output_si_large(self):
 
     def test_input_output_si_small(self):
         """
-        Large (>1) numbers input matches output
+        Small (<1) numbers input matches output
         """
 
         for num in ('100.00m', '10.00m', '1.00m',
@@ -317,7 +316,18 @@ def test_input_output_iec(self):
             self.assertEqual(format(Float('+' + num), '.2k'), num)
             self.assertEqual(format(Float('+' + num), '.2m'), short_form)
 
-    def test_unicode(self):
+    def test_micro(self):
+        """
+        Micro and mu are both valid for input
+        """
+
+        micro = '100.01µ'
+        mu = '100.01μ'
+
+        self.assertEqual(format(Float(mu), '.2h'), mu)
+        self.assertEqual(format(Float(micro), '.2h'), mu)
+
+    def test_unicode_iec(self):
         """
         For Python 2, test Unicode strings behave the same
         """
@@ -486,6 +496,7 @@ def test_deprecated(self):
         self.assertEqual(format(Float(2048), u'.2J'), '2.00K')
 
 
+# pylint: disable=expression-not-assigned
 class TestFloatMath(unittest.TestCase):
     """
     Tests for prefixed.Float math