Convert relative paths to absolute paths when collecting with Python

collection, sometimes need to collect pictures, but some of the site's pictures provide relative address, it is best to convert to absolute address

In the scrapy, there are the following resolution strategies

Http://stackoverflow.com/questions/6499603/python-scrapy-convert-relative-paths-to-absolute-paths

Http://stackoverflow.com/questions/19970015/scrapy-item-loader-to-get-a-absolute-url-from-extracted-url

Using the conversion method in lxml, refer to

Http://qiita.com/podhmo/items/e03431c718b94d6304ff