Removing items from a set – remove(), pop(), and difference

Python gives us several ways to remove items from a set collection. We can use the remove() method to remove a specific item. We can use the pop() method to remove (and return) an arbitrary item.

Additionally, we can compute a new set using the set intersection, difference, and symmetric difference operators: &, -, and ^. These will produce a new set that is a subset of a given input set.

Getting ready

Sometimes, we'll have log files that contain lines with complex and varied formats. Here's a small snippet from a long, complex log:

[2016-03-05T09:29:31-05:00] INFO: Processing ruby_block[print IP] action run (@recipe_files::/home/slott/ch4/deploy.rb line 9)
[2016-03-05T09:29:31-05:00] INFO: Installed IP: 111.222.111.222
[2016-03-05T09:29:31-05:00] INFO: ruby_block[print IP] called
 - execute the ruby block print IP
[2016-03-05T09:29:31-05:00] INFO: Chef Run complete in 23.233811181...