Page 311 - Beginning Programming with Pyth - John Paul Mueller

FIGURE 13-19: String functions let you easily format your output in specific ways.
FIGURE 13-20: Use the format() function to obtain specific kinds of output from your application.
This section touches on only some of the common techniques used to format output in Python. There are lots more. You see many of these approaches demonstrated in the chapters that follow. The essential goal is to use a technique that's easy to read, works well with all anticipated inputs, and doesn’t paint you into a corner when you’re creating additional output later.
Working with the Counter Object
Sometimes you have a data source and you simply need to know how often things happen (such as the appearance of a certain item in the list). When you have a short list, you can simply count the items. However, when you have a really long list, getting an accurate count is nearly impossible. For example, consider what it would take if you had a really long novel like War and Peace in a list and wanted to know the frequency of the words the novel used. The task would be impossible without a computer.
The Counter object lets you count items quickly. In addition, it’s incredibly easy to use. This book shows the Counter object in use a number of times, but this chapter shows how to use it specifically with lists. The example in this section creates a list with repetitive elements