X-Git-Url: https://wannabe.guru.org/gitweb/?a=blobdiff_plain;f=conversion_utils.py;h=d2225fdb2b2f37b78320ee03b07a27be6ade45ac;hb=d82c8377ce394cad812dc0d53829f7465b3f3f4e;hp=b83d62e4daf50ec76850e047672069a8e9f47c7b;hpb=a838c154135b2420d9047a101caf24a2c9f593c2;p=python_utils.git

diff --git a/conversion_utils.py b/conversion_utils.py
index b83d62e..d2225fd 100644
--- a/conversion_utils.py
+++ b/conversion_utils.py
@@ -7,11 +7,27 @@ import constants
 
 
 class Converter(object):
+    """A converter has a canonical name and a category.  The name defines
+    a unit of measurement in a category or class of measurements.
+    This framework will allow conversion between named units in the
+    same category.  e.g. name may be "meter", "inch", "mile" and their
+    category may be "length".
+
+    The way that conversions work is that we convert the magnitude
+    first to a canonical unit and then (if needed) from the canonical
+    unit to the desired destination unit.  e.g. if "meter" is the
+    canonical unit of measurement for the category "length", in order
+    to convert miles into inches we first convert miles into meters
+    and, from there, meters into inches.  This is potentially
+    dangerous because it requires two floating point operations which
+    each have the potential to overflow, underflow, or introduce
+    floating point errors.  Caveat emptor.
+    """
     def __init__(self,
                  name: str,
                  category: str,
-                 to_canonical: Callable,
-                 from_canonical: Callable,
+                 to_canonical: Callable,   # convert to canonical unit
+                 from_canonical: Callable, # convert from canonical unit
                  unit: str) -> None:
         self.name = name
         self.category = category
@@ -29,6 +45,7 @@ class Converter(object):
         return self.unit
 
 
+# A catalog of converters.
 conversion_catalog = {
     "Second": Converter("Second",
                         "time",
@@ -94,90 +111,225 @@ def _convert(magnitude: Number,
 
 
 def sec_to_min(s: float) -> float:
+    """
+    Convert seconds into minutes.
+
+    >>> sec_to_min(120)
+    2.0
+    """
     return convert(s, "Second", "Minute")
 
 
 def sec_to_hour(s: float) -> float:
+    """
+    Convert seconds into hours.
+
+    >>> sec_to_hour(1800)
+    0.5
+    """
     return convert(s, "Second", "Hour")
 
 
 def sec_to_day(s: float) -> float:
+    """
+    Convert seconds into days.
+
+    >>> sec_to_day(1800)
+    0.020833333333333332
+    """
     return convert(s, "Second", "Day")
 
 
 def sec_to_week(s: float) -> float:
+    """
+    Convert seconds into weeks.
+
+    >>> sec_to_week(1800)
+    0.002976190476190476
+    """
     return convert(s, "Second", "Week")
 
 
 def min_to_sec(m: float) -> float:
+    """
+    Convert minutes into seconds.
+
+    >>> min_to_sec(5)
+    300.0
+    """
     return convert(m, "Minute", "Second")
 
 
 def min_to_hour(m: float) -> float:
+    """
+    Convert minutes into hours.
+
+    >>> min_to_hour(120)
+    2.0
+    """
     return convert(m, "Minute", "Hour")
 
 
 def min_to_day(m: float) -> float:
+    """
+    Convert minutes into days.
+
+    >>> min_to_day(60 * 12)
+    0.5
+    """
     return convert(m, "Minute", "Day")
 
 
 def min_to_week(m: float) -> float:
+    """
+    Convert minutes into weeks.
+
+    >>> min_to_week(60 * 24 * 3)
+    0.42857142857142855
+    """
     return convert(m, "Minute", "Week")
 
 
 def hour_to_sec(h: float) -> float:
+    """
+    Convert hours into seconds.
+
+    >>> hour_to_sec(1)
+    3600.0
+    """
     return convert(h, "Hour", "Second")
 
 
 def hour_to_min(h: float) -> float:
+    """
+    Convert hours into minutes.
+
+    >>> hour_to_min(2)
+    120.0
+    """
     return convert(h, "Hour", "Minute")
 
 
 def hour_to_day(h: float) -> float:
+    """
+    Convert hours into days.
+
+    >>> hour_to_day(36)
+    1.5
+    """
     return convert(h, "Hour", "Day")
 
 
 def hour_to_week(h: float) -> float:
+    """
+    Convert hours into weeks.
+
+    >>> hour_to_week(24)
+    0.14285714285714285
+    """
     return convert(h, "Hour", "Week")
 
 
 def day_to_sec(d: float) -> float:
+    """
+    Convert days into seconds.
+
+    >>> day_to_sec(1)
+    86400.0
+    """
     return convert(d, "Day", "Second")
 
 
 def day_to_min(d: float) -> float:
+    """
+    Convert days into minutes.
+
+    >>> day_to_min(0.1)
+    144.0
+    """
     return convert(d, "Day", "Minute")
 
 
 def day_to_hour(d: float) -> float:
+    """
+    Convert days into hours.
+
+    >>> day_to_hour(1)
+    24.0
+    """
     return convert(d, "Day", "Hour")
 
 
 def day_to_week(d: float) -> float:
+    """
+    Convert days into weeks.
+
+    >>> day_to_week(14)
+    2.0
+    """
     return convert(d, "Day", "Week")
 
 
 def week_to_sec(w: float) -> float:
+    """
+    Convert weeks into seconds.
+
+    >>> week_to_sec(10)
+    6048000.0
+    """
     return convert(w, "Week", "Second")
 
 
 def week_to_min(w: float) -> float:
+    """
+    Convert weeks into minutes.
+
+    >>> week_to_min(1)
+    10080.0
+    """
     return convert(w, "Week", "Minute")
 
 
 def week_to_hour(w: float) -> float:
+    """
+    Convert weeks into hours.
+
+    >>> week_to_hour(1)
+    168.0
+    """
     return convert(w, "Week", "Hour")
 
 
 def week_to_day(w: float) -> float:
+    """
+    Convert weeks into days.
+
+    >>> week_to_day(1)
+    7.0
+    """
     return convert(w, "Week", "Day")
 
 
 def f_to_c(temp_f: float) -> float:
-    """Fahrenheit to Celsius."""
+    """
+    Convert Fahrenheit into Celsius.
+
+    >>> f_to_c(32.0)
+    0.0
+    """
     return convert(temp_f, "Fahrenheit", "Celsius")
 
 
 def c_to_f(temp_c: float) -> float:
-    """Celsius to Fahrenheit."""
+    """
+    Convert Celsius to Fahrenheit.
+
+    >>> c_to_f(0.0)
+    32.0
+    """
     return convert(temp_c, "Celsius", "Fahrenheit")
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()