The way to find a good topic is to read some recent articles. That is the key to success, and sometimes I think professors do not tell students about it clearly. Choosing a topic is the best part of writing a research article, because it gives you an opportunity to read some recent articles about the area that interests you. So, maybe you will search google for professional journals that cover computer science topics, and you'll find some of the most recent articles. The articles written most recently are like the comments people just made a moment ago in a conversation about the topic. They represent the best ideas humanity has developed through years of research. A recent article will also have a literature review about the topic, so you can quickly become an expert. Then, you will know all about what has been said in the conversation about datamining, etc., and you can say something to intelligently contribute. A research article is like one comment made in a conversation that takes place among many people.