#WRITING A WEBSCRAPER HOW TO#

To download a copy of the White House's homepage, including all of its visual elements, you simply type: wget -k -p You run wget from the command-line by specifying a target URL and options. You can find download and installation instructions at its homepage: If you've had prior experience with the command-line, then you may know of wget, a powerful program that lets you mirror websites in a single line. This chapter will list examples of the common structures for so that you'll have a general blueprint for scraping any given website. This is why learning enough code to write your own scraper will ultimately be a better investment than any commercial ready-made web-scraper you can buy. There's no one kind of program that will scrape the variety of the world's websites with the specificity that you'll need to find interesting, organized data. Other times, the scraper will have to process information from one page to figure out where to go next.

#WRITING A WEBSCRAPER HOW TO#

The next piece of the puzzle is how to program a scraper that navigates the relevant parts of a website. If the raw data isn't already in spreadsheet-ready form, the Nokogiri gem makes it especially simple to extract the data from HTML. The browser's web inspector provides a point-and-click interface to see where page elements are described in the raw HTML and to examine the raw data going in and out of your browser. In the previous chapters on web-scraping, we saw how scraping data from webpages doesn't require a deep knowledge of HTML.

Writing a webscraper