<p>更复杂但更灵活的版本:</p>
<pre><code>units = {
'kg': ('weight', 1.),
'kilo': ('weight', 1.),
'kilogram': ('weight', 1.),
'lb': ('weight', 2.204),
'pound': ('weight', 2.204),
'tonne': ('weight', 0.001),
'carat': ('weight', 5000.),
'gram': ('weight', 1000.),
'dram': ('weight', 564.4),
'ounce': ('weight', 35.27),
'grain': ('weight', 15430.),
'm': ('distance', 1.),
'meter': ('distance', 1.),
'kilometer': ('distance', 0.001),
'km': ('distance', 0.001),
'centimeter': ('distance', 100.),
'cm': ('distance', 100.),
'meter': ('distance', 1.),
'mile': ('distance', 0.0006214),
'chain': ('distance', 0.04971),
'furlong': ('distance', 0.004971),
'league': ('distance', 0.0002071),
'foot': ('distance', 3.281),
'feet': ('distance', 3.281), # irregular plural - must be explicitly specified!
'inch': ('distance', 39.37)
}
def getUnit(unit_name):
if unit_name in units:
return units[unit_name]
# recognize regular plural forms
elif unit_name.endswith('es') and unit_name[:-2] in units:
return units[unit_name[:-2]]
elif unit_name.endswith('s') and unit_name[:-1] in units:
return units[unit_name[:-1]]
# not found?
else:
raise ValueError("Unrecognized unit '{0}'".format(unit_name))
def convert(amt, from_unit, to_unit):
typeA, numA = getUnit(from_unit)
typeB, numB = getUnit(to_unit)
if typeA==typeB:
return amt * numB / numA
else:
raise ValueError("Units are of different types ('{0}' and '{1}')".format(typeA, typeB))
def conversion(s):
"""
Do unit conversion
Accepts a string of the form
"(number) (unitA) [to] (unitB)"
If unitA and unitB are of the same unit-type, returns the converted value.
"""
s = s.strip().lower().split()
if len(s) not in (3, 4):
raise ValueError("Argument string has wrong number of words (should be three or four)")
try:
amt = float(s[0])
except ValueError:
raise ValueError("Argument string must start with a number")
from_unit = s[1]
to_unit = s[-1]
return convert(amt, from_unit, to_unit)
def tryAgain():
s = raw_input('Try again (Y/n)? ').strip().lower()
return 'yes'.startswith(s)
def main():
while True:
s = raw_input("Convert what? (ex: 10 meters to feet) ")
try:
print(": {0}".format(conversion(s)))
except ValueError, v:
print v
if not tryAgain():
break
if __name__=="__main__":
main()
</code></pre>
<p>这可以解决“10吨到盎司”或“30毛到英尺”这样的问题。</p>
<p>建议进一步补充:</p>
<ol>
<li><p>添加纳米作为距离单位(并进行测试)。</p></li>
<li><p>加短吨和石头作为重量单位(并进行测试)。</p></li>
<li><p>添加升、品脱和桶作为体积单位(并进行测试)。</p></li>
</ol>