http://rcharlie.com/2017-02-16-fitteR-happieR/
Edit: sorry, I misremembered - it actually handled "True Love Waits" pretty well. It did pick up "Fitter Happier" as one of the happiest, that's what struck me as strange.
>We have a winner! “True Love Waits” is officially the single most depressing Radiohead song to date. Rightly so, given that it tied for lowest valence (0.0378) and ranked fourth for highest percentage of sad words (24%). If the numbers still don’t convince you, just listen to it.
The colour gradient on the graph is confusing - does green mean happy, blue unhappy, and the movie changes tone over time? Axes of the graph are not labeled, what are we looking at? But, those concerns are secondary.
Bar graph seems a poor choice here, given the nature of the data. Given that there doesn't seem to be any correlation with time, the order of phrases doesn't seem important -- you could forgo the linear presentation, and display the distribution of the data instead.
For example, you could bucket the sentiment values (-3 to -2, -2 to -1, etc) and use a histogram to show the counts in each bucket. This would enable you to compare different movies (one histogram per movie).
I haven't confirmed by looking at the source, but my suspicion is that either most sentiment analysis implementations are rule based or are not well tuned.
My go-to example is IBM Watson's sentiment analysis service rating "I hope you die" as very positive because the sentence is categorized as "hopeful". Which I suppose it is, technically, and perhaps this is a case where I'm expecting too much because recognizing this particular example as having a negative sentiment requires much human abstract reasoning and inference, but the example remains nonetheless because real-world language usage that isn't dry and technical is rife with these sorts of linguistic usages.
just found it on google
Curious if you investigated other libraries or algorithms. have you seen this - i have been playing with it, seems reliable: https://github.com/cjhutto/vaderSentiment