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Modern Python Cookbook

You're reading from   Modern Python Cookbook The latest in modern Python recipes for the busy modern programmer

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Product type Paperback
Published in Nov 2016
Publisher Packt
ISBN-13 9781786469250
Length 692 pages
Edition 1st Edition
Languages
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Toc

Table of Contents (12) Chapters Close

Preface 1. Numbers, Strings, and Tuples 2. Statements and Syntax FREE CHAPTER 3. Function Definitions 4. Built-in Data Structures – list, set, dict 5. User Inputs and Outputs 6. Basics of Classes and Objects 7. More Advanced Class Design 8. Input/Output, Physical Format, and Logical Layout 9. Testing 10. Web Services 11. Application Integration

Deleting from a list of mappings

Removing items from a list has an interesting consequence. Specifically, when item list[x] is removed, one of two other things will happen:

  • Item list[x+1] takes the place of list[x]
  • Item x+1 == len(list) takes the place of list[x] because x was the last index in the list

These are side-effects that happen in addition to removing an item. Because things can move around in a list, it makes deleting more than one item at a time challenging.

When the list contains items that have a definition for the __eq__() special method, then the list remove() method can remove each item. When the list items don't have a simple __eq__() test, then it becomes more challenging to remove multiple items from the list.

How can we delete multiple items from a list?

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