Unit converter done

Author: Karan Goel

Numbers/unit.py

@@ -0,0 +1,91 @@
+"""
+Unit Converter (temp, currency, volume, mass and more) - Converts
+various units between one another. The user enters the type of unit
+being entered, the type of unit they want to convert to and then
+the value. The program will then make the conversion.
+"""
+
+from __future__ import division
+from urllib2 import urlopen
+import json
+
+# 1 (std unit) = these many units
+MULTIPLIERS_TO_STD = {
+    'length': {
+        'cm': 0.01,
+        'm': 1, # std unit
+        'km': 1000,
+        'mi': 1609.34,
+        'ft': 0.3048
+        },
+    'temp': {
+        'C': 1, # std unit
+        'F': 33.8
+        }
+}
+
+# These many units = 1 (std unit)
+MULTIPLIERS_FROM_STD = {
+    'length': {
+        'cm': 100,
+        'm': 1, # std unit
+        'km': 0.001,
+        'mi': 0.000621371,
+        'ft': 3.28084
+        },
+    'temp': {
+        'C': 1, # std unit
+        'F': -17.2222
+        }
+}
+
+
+def get_user_input(choice):
+    units = ', '.join(MULTIPLIERS_TO_STD[choice].keys())
+    source_unit = raw_input('\nEnter source unit (%s): ' % units)
+    source_val = float(raw_input('How many %s\'s? ' % source_unit))
+    convert_to = raw_input('Convert to? (%s): ' % units)
+    return source_unit, source_val, convert_to
+
+def get_currency(source_unit, source_val, convert_to):
+    url = 'http://rate-exchange.appspot.com/currency?from=%s&to=%s&q=%s' % (
+        source_unit, convert_to, str(source_val))
+    content = urlopen(url).read()
+    return json.loads(content)['v']
+
+def main():
+    print """Unit Converter
+    1. Length
+    2. Temperature
+    3. Currency"""
+
+    choice = int(raw_input('What do you want to convert: '))
+
+    if choice == 1:
+        source_unit, source_val, convert_to = get_user_input('length')
+        print '%f%s = %f%s' % (source_val, source_unit,
+                               source_val * \
+                               MULTIPLIERS_TO_STD['length'][source_unit] * \
+                               MULTIPLIERS_FROM_STD['length'][convert_to], \
+                               convert_to)
+    elif choice == 2:
+        source_unit, source_val, convert_to = get_user_input('temp')
+        if (source_unit, convert_to) == ('F', 'C'): # F -> C
+            value = (source_val - 32) * (5/9)
+        elif (source_unit, convert_to) == ('C', 'F'): # C -> F
+            value = (source_val * (9/5)) + 32
+        else:
+            value = source_val
+        print '%f%s = %f%s' % (source_val, source_unit,
+                               value, convert_to)
+
+    elif choice == 3:
+        source_unit = raw_input('\nEnter source currency (eg USD, INR etc): ')
+        source_val = float(raw_input('How many %s\'s? ' % source_unit))
+        convert_to = raw_input('Convert to? (eg USD, INR etc): ')
+        print '%f%s = %f%s' % (source_val, source_unit,
+                               get_currency(source_unit, source_val, convert_to),
+                               convert_to)
+        
+if __name__ == '__main__':
+    main()