wordnet semantic similarity: how to refer to elements of a pair in a list? can we sort dictionary according to the value?

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Dear all, the problem has been solved as follows. Thanks anyway:
>>> import nltk
>>> from nltk.corpus import wordnet as wn
>>> pairs = {'car':'automobile', 'gem':'jewel', 'journey':'voyage'}
>>> list_simi=[]
>>> for key in pairs:
	word1 = wn.synset(str(key) + '.n.01') 
        word2 = wn.synset(str(pairs[key])+'.n.01') 
        similarity = word1.path_similarity(word2) 
        list_simi.append((key+'-'+pairs[key],similarity))

        
>>> from operator import itemgetter
>>> sorted(list_simi, key=itemgetter(1), reverse=False)
[('gem-jewel', 0.125), ('journey-voyage', 0.25), ('car-automobile', 1.0)]
>>> sorted(list_simi, key=itemgetter(1), reverse=True)
[('car-automobile', 1.0), ('journey-voyage', 0.25), ('gem-jewel', 0.125)]
>>> sorted(list_simi, key=itemgetter(1))
[('gem-jewel', 0.125), ('journey-voyage', 0.25), ('car-automobile', 1.0)]