Below a simple example of sentiment analyis of tweets about tyre competitors. Notes:
- x-axes=positive tweets
- y-axes=negative tweets
- positive and negative words: Hu and Liu’s “opinion lexicon” categorizes nearly 6,800 words as positive or negative and were downloaded from Bing Liu’s web site: http://www.cs.uic.edu/~liub/FBS/opinion-lexicon-English.rar
- only more positive and worst negative tweets are collected
The code can be found here.
Gabriele Martinelli 
ciao, non e’ che per caso sai se esiste una lista simile di parole positive/negative anche in italiano? grazie!
Interesting use… This exact twitteR package and the Hu/Liu corpus were the inspiration for a Twitter sentiment analysis Android app we wrote called TxtMiner, http://bit.ly/Axxoju