Getting an element from tuple of tuples in python [duplicate]

Question

Possible Duplicate:
Tuple value by key

How do i find the country name by having its code,

COUNTRIES = (
   ('AF', _(u'Afghanistan')),
   ('AX', _(u'\xc5land Islands')),
   ('AL', _(u'Albania')),
   ('DZ', _(u'Algeria')),
   ('AS', _(u'American Samoa')),
   ('AD', _(u'Andorra')),
   ('AO', _(u'Angola')),
   ('AI', _(u'Anguilla'))
)

I have code AS, find its name without using forloop on COUNTRIES tuple?

Answer 1

You can simply do:

countries_dict = dict(COUNTRIES)  # Conversion to a dictionary mapping
print countries_dict['AS']

This simply creates a mapping between country abbreviations and country names. Accessing the mapping is very fast: this is probably the fastest method if you do multiple lookups, as Python's dictionary lookup is very efficient.

Answer 2

COUNTRIES = (
   ('AF', (u'Afghanistan')),
   ('AX', (u'\xc5land Islands')),
   ('AL', (u'Albania')),
   ('DZ', (u'Algeria')),
   ('AS', (u'American Samoa')),
   ('AD', (u'Andorra')),
   ('AO', (u'Angola')),
   ('AI', (u'Anguilla'))
)

print (country for (code, country) in COUNTRIES if code=='AD').next()
#>>> Andorra

print next((country for (code, country) in COUNTRIES if code=='AD'), None)
#Andorra
print next((country for (code, country) in COUNTRIES if code=='Blah'), None)
#None

# If you want to do multiple lookups, the best is to make a dict:
d = dict(COUNTRIES)
print d['AD']
#>>> Andorra