The basics of sentiment analysis

To begin a sentiment mining project, we first need to understand how opinions are structured in text so we can find the best way to train the computer to deal with them. Opinion mining and sentiment analysis are considered sub-problems of the much larger field of natural language processing (NLP), and as such, are subject to many of the same unsolved issues in trying to account for all the quirks of human communication. However, sentiment mining is restricted in an important way, namely that its goal is not to understand the statements made by people, but rather to just figure out their tone. As we will see later, any one strategy for finding the sentiment of any given text may not be perfect, but this may not matter much if the amount of data is high and the stakes are comparatively low.

The structure of an opinion

Each opinion typically has a target. If we read the sentence, "This was the worst movie I ever saw," the target of that opinion is the...