As a demonstration of efforts in estimating happiness from language, Hedonometer charts emotion over time for literary classics. The above is the collection of charts for Adventures of Huckleberry Finn by Mark Twain.
I wish I could say this meant something to me, but comparative literature in high school was never my strong suit. From a totally superficial point of view though, the chart in the top left shows happiness metrics — based on the research of Peter Dodds and Chris Danforth — through the entirety of the book. The chart on the right shows a comparison of book sections, which you can select in the first chart.