Using stacked generator expressions

In the Writing generator functions with the yield statement recipe, we created a simple generator function that performed a single transformation on a piece of data. As a practical matter, we often have several functions that we'd like to apply to incoming data.

How can we stack or combine multiple generator functions to create a composite function?

Getting ready

We have a spreadsheet that is used to record fuel consumption on a large sailboat. It has rows which look like this:

date	engine on	fuel height
	engine off	fuel height
	Other notes
10/25/2013	08:24	29
	13:15	27
	calm seas - anchor solomon's island
10/26/2013	09:12	27
	18:25	22
	choppy - anchor in jackson's creek

For more background on this data, see the Slicing and dicing a list recipe in Chapter 4, Built-in Data Structures – list, set, dict.

As a sidebar, we can take the data like this. We'll look at this in detail in the Reading delimited files with the csv module recipe in...