Deleting from a list – deleting, removing, popping, and filtering

There are many times when we want to remove items from a list collection. We might delete items from a list, and then process the items which are left over.

Removing unneeded items has a similar effect as using the filter() to create a copy which has only the needed items. The distinction is that a filtered copy will use more memory than deleting items from a list. We'll show both techniques for removing unwanted items from a list.

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
	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.

We can read the data like this:

>>> from pathlib import Path 
>>> import csv 
>>> with Path('code/fuel.csv').open...