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 an arbitrary item.

Additionally, we can compute a new set using set intersection, difference, and symmetric difference operators: &, -, and ^. These will produce a new set which 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:

>>> 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 seconds 
....