Processing text using regular expressions

The web consists predominantly of unstructured text. One of the main tasks in web scraping is to collect the relevant information from heaps of textual data. Within the unstructured text we are often interested in specific information, especially when we want to analyze the data using quantitative methods. Specific information can include numbers such as phone numbers, zip codes, latitude, longitude, or addresses.

First, we gather the unstructured text, next we determine the recurring patterns behind the information we are looking for, and then we apply these patterns to the unstructured text to extract the information. When we are web scraping, we have to identify and extract those parts of the document that contain the relevant information. Ideally, we can do so using xpath althrough, sometimes the crucial information is hidden within values. Sometimes relevant information might be scattered across an HTML document. We need to write regular expressions...