pronounce scientific notation

mycroft/util/format.py

@@ -89,7 +89,8 @@ def nice_time(dt, lang="en-us", speech=True, use_24hour=False,
     return str(dt)
 
 
-def pronounce_number(number, lang="en-us", places=2, short_scale=True):
+def pronounce_number(number, lang="en-us", places=2, short_scale=True,
+                     scientific=False):
     """
     Convert a number to it's spoken equivalent
 
@@ -99,13 +100,15 @@ def pronounce_number(number, lang="en-us", places=2, short_scale=True):
         number: the number to pronounce
         short_scale (bool) : use short (True) or long scale (False)
             https://en.wikipedia.org/wiki/Names_of_large_numbers
+        scientific (bool) : convert and pronounce in scientific notation
     Returns:
         (str): The pronounced number
     """
     lang_lower = str(lang).lower()
     if lang_lower.startswith("en"):
         return pronounce_number_en(number, places=places,
-                                   short_scale=short_scale)
+                                   short_scale=short_scale,
+                                   scientific=scientific)
     elif lang_lower.startswith("it"):
         return pronounce_number_it(number, places=places)
     elif lang_lower.startswith("fr"):

mycroft/util/lang/format_en.py

@@ -221,7 +221,7 @@ def nice_number_en(number, speech, denominators):
     return return_string
 
 
-def pronounce_number_en(num, places=2, short_scale=True):
+def pronounce_number_en(num, places=2, short_scale=True, scientific=False):
     """
     Convert a number to it's spoken equivalent
 
@@ -232,9 +232,18 @@ def pronounce_number_en(num, places=2, short_scale=True):
         places(int): maximum decimal places to speak
         short_scale (bool) : use short (True) or long scale (False)
             https://en.wikipedia.org/wiki/Names_of_large_numbers
+        scientific (bool): pronounce in scientific notation
     Returns:
         (str): The pronounced number
     """
+    if scientific:
+        number = '%E' % num
+        n, power = number.replace("+", "").split("E")
+        power = int(power)
+        if power != 0:
+            return pronounce_number_en(float(n), places, short_scale, False) + \
+                   " times ten to the power of " + \
+                   pronounce_number_en(power, places, short_scale, False)
     if short_scale:
         number_names = NUM_STRING_EN.copy()
         number_names.update(SHORT_SCALE_EN)

test/unittests/util/test_format.py

@@ -166,6 +166,20 @@ class TestPronounceNumber(unittest.TestCase):
                          "and thirty nine million, six hundred and thirty one "
                          "thousand, eight hundred and ninety three")
 
+    def test_convert_scientific_notation(self):
+        self.assertEqual(pronounce_number(0, scientific=True), "zero")
+        self.assertEqual(pronounce_number(33, scientific=True),
+                         "three point three times ten to the power of one")
+        self.assertEqual(pronounce_number(299792458, scientific=True),
+                         "two point nine nine times ten to the power of eight")
+        self.assertEqual(pronounce_number(299792458, places=6,
+                                          scientific=True),
+                         "two point nine nine seven nine two five times "
+                         "ten to the power of eight")
+        self.assertEqual(pronounce_number(1.672e-27, places=3,
+                                          scientific=True),
+                         "one point six seven two times ten to the power of "
+                         "negative twenty seven")
 
 # def nice_time(dt, lang="en-us", speech=True, use_24hour=False,
 #              use_ampm=False):