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Python Essentials

You're reading from   Python Essentials Modernize existing Python code and plan code migrations to Python using this definitive guide

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Product type Paperback
Published in Jun 2015
Publisher Packt
ISBN-13 9781784390341
Length 298 pages
Edition 1st Edition
Languages
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Author (1):
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Steven F. Lott Steven F. Lott
Author Profile Icon Steven F. Lott
Steven F. Lott
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Toc

Table of Contents (17) Chapters Close

Preface 1. Getting Started FREE CHAPTER 2. Simple Data Types 3. Expressions and Output 4. Variables, Assignment and Scoping Rules 5. Logic, Comparisons, and Conditions 6. More Complex Data Types 7. Basic Function Definitions 8. More Advanced Functions 9. Exceptions 10. Files, Databases, Networks, and Contexts 11. Class Definitions 12. Scripts, Modules, Packages, Libraries, and Applications 13. Metaprogramming and Decorators 14. Fit and Finish – Unit Testing, Packaging, and Documentation 15. Next Steps Index

Using the head, *tail assignment

When working with sequences, there are some algorithms which work by separating the head of the sequence from the rest of the sequence. We can do this with a variation on the assignment statement. We like to call this the head, *tail = assignment statement.

Let's say that we have an input string with a list of values, something like this:

>>> line = "255  73 108 Radical Red"
>>> line.split()
['255', '73', '108', 'Radical', 'Red']

We have split the string into space-delimited words with line.split(). In this case, the head of the list is the first three fields of the red, green, and blue elements of a color. The tail is all the remaining fields, which is the name parsed into separate words.

We can use head, *tail = assignment to split the first three fields from the remaining files.

It looks like this:

>>> r, g, b, *name = line.split()
>>> g
'73'
&gt...
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