from pattern.en import sentiment
polarity, subjectivity = sentiment("excessively affluent")
print polarity
print subjectivity
Polarity is a positive/negative score, subjectivity is a neutral/subjective score. Some expressions can be subjective without necessarily being positive or negative.
For English, you can also use SentiWordnet with Pattern. You can request the lexicon (for research purposes) from:
http://sentiwordnet.isti.cnr.it/
And place it in pattern/text/en/wordnet
Then:
from pattern.en import wordnet
print wordnet.sentiwordnet("excessively")
print wordnet.sentiwordnet("affluent")
Some more documentation is here:
http://www.clips.ua.ac.be/pages/pattern-en#wordnet
The differences are that
1) SentiWordnet has a score for all words while the lexicons in Pattern are optimized for the most frequent adjectives,
2) the lexicons in Pattern deal with successive words, e.g., in "excessively affluent", "excessively" boosts or dampens the score of "affluent", instead of having a score itself.
Depending on what you want to do it can be more interesting to have a score for all kinds of words (= SWN), or just adjectives that occur frequently in product reviews (= Pattern lexicons).
Grz,
Tom