Python 中的简单单位转换器

Question

我是编程新手，我正在尝试用 python 制作一个简单的单位转换器。我想将公制单位和公制单位转换为英制单位，反之亦然。我已经开始使用这段代码，但发现这种方法速度慢且效率低下，如何才能更有效地编写代码？

 import math
import time
"""Unit Converter"""
#variable setting
cat = raw_input ("Which category would you like to convert? we support length(l) and Weight(w):  ")
if cat == ("l"):
unit1 = raw_input ("Which unit would you like to convert from: ")
unit2 = raw_input ("Which unit would you like to convert to: ")
num1 = raw_input ("Enter your value: " )

    ##Calculations

if unit1 == "cm" and unit2 == "m":
    ans = float(num1)/100
elif unit1 == "mm" and unit2 == "cm":
    ans = float(num1)/10
elif unit1 == "m" and unit2 == "cm":
    ans = float(num1)*100
elif unit1 == "cm" and unit2 == "mm":
    ans = float(num1)*10
elif unit1 == "mm" and unit2 == "m":
    ans = float(num1)/1000
elif unit1 == "m" and unit2 == "mm":
    ans = float(num1)*1000
elif unit1 == "km" and unit2 == "m":
    ans = float(num1)*1000
elif unit1 == "m" and unit2 == "km":
    ans = float(num1)/1000
elif unit1 == "mm" and unit2 == "km":
    ans = float(num1)/1000000

谢谢你的帮助。

原文由 SalamalCamel 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

您可以使用带有转换因子的字典和调用它们的函数。

 def convert_SI(val, unit_in, unit_out):
    SI = {'mm':0.001, 'cm':0.01, 'm':1.0, 'km':1000.}
    return val*SI[unit_in]/SI[unit_out]

例子：

 >>> convert_SI(1, 'm', 'km')
0.001
>>> convert_SI(1, 'km', 'm')
1000.0
>>> convert_SI(1, 'cm', 'm')
0.01

原文由 ryanjdillon 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 2

对于那些喜欢使用外部包的人来说， Axiompy 是一个选择。

安装： pip install axiompy

 from axiompy import Units
units = Units()
print(units.unit_convert(3 * units.metre, units.foot))
>>> <Value (9.84251968503937 <Unit (foot)>)>

原文由 anonymousse 发布，翻译遵循 CC BY-SA 4.0 许可协议