Introduction to Python for Science and Engineering

389 Pages·2019·5.22 MB·English

by  David J. Pine

Introduction to
Python for Science
and Engineering
Series in Computational Physics
Parallel Science and Engineering Applications: The Charm++ Approach
Laxmikant V. Kale, Abhinav Bhatele
Introduction to Numerical Programming: A Practical Guide for Scientists and Engi-
neers Using Python and C/C++
Titus A. Beu
Computational Problems for Physics: With Guided Solutions Using Python
Rubin H. Landau, Manual José Páez
Introduction to Python for Science and Engineering
David J. Pine
For more information about this series, please visit: https://www.crcpress.com/
Series-in-Computational-Physics/book-series/CRCSERCOMPHY
Introduction to
Python for Science
and Engineering
David J. Pine
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Library of Congress Cataloging‑in‑Publication Data
Names: Pine, David J., author.
Title: Introduction to Python for science and engineering / by David J. Pine.
Description: Boca Raton, Florida : CRC Press, [2019] | Series: Series in
computational physics | Includes bibliographical references and index.
Identifiers: LCCN 2018027880 (print) | LCCN 2018051956 (ebook) | ISBN
9780429506413 (eBook General) | ISBN 9780429014253 (eBook Adobe Reader) |
ISBN 9780429014246 (eBook ePub) | ISBN 9780429014239 (eBook Mobipocket) |
ISBN 9781138583894 (paperback : acid-free paper) | ISBN 9781138583900
(hardback : acid-free paper).
Subjects: LCSH: Python (Computer program language) | Computer programming. |
Engineering--Data processing. | Science--Data processing.
Classification: LCC QA76.73.P98 (ebook) | LCC QA76.73.P98 P58 2019 (print) |
DDC 005.13/3--dc23
LC record available at https://lccn.loc.gov/2018027880
Visit the Taylor & Francis Web site at
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To Alex Pine
who introduced me to Python

Contents
Preface xv
AbouttheAuthor xix
1 Introduction 1
1.1 IntroductiontoPythonforScienceandEngineering . 1
2 LaunchingPython 3
2.1 InteractingwithPython . . . . . . . . . . . . . . . . . 3
2.2 InstallingPythononYourComputer . . . . . . . . . . 4
2.3 TheSpyderWindow . . . . . . . . . . . . . . . . . . . 4
2.4 TheIPythonPane . . . . . . . . . . . . . . . . . . . . . 4
2.4.1 Magiccommands . . . . . . . . . . . . . . . . . 6
2.4.2 Systemshellcommands . . . . . . . . . . . . . 8
2.4.3 Tabcompletion . . . . . . . . . . . . . . . . . . 8
2.4.4 Recapofcommands . . . . . . . . . . . . . . . . 9
2.5 InteractivePythonasaCalculator . . . . . . . . . . . 9
2.5.1 BinaryarithmeticoperationsinPython . . . . . 10
2.5.2 Typesofnumbers . . . . . . . . . . . . . . . . . 10
2.5.3 ImportantnoteonintegerdivisioninPython . 12
2.6 Variables . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.6.1 Namesandtheassignmentoperator . . . . . . 13
2.6.2 Legalandrecommendedvariablenames . . . . 14
2.6.3 ReservedwordsinPython . . . . . . . . . . . . 15
2.7 ScriptFilesandPrograms . . . . . . . . . . . . . . . . 16
2.7.1 Firstscriptingexample:TheEditorpane . . . . 16
2.8 PythonModules . . . . . . . . . . . . . . . . . . . . . . 18
2.8.1 Pythonmodulesandfunctions:Afirstlook . . 20
2.8.2 SomeNumPyfunctions . . . . . . . . . . . . . . 22
2.8.3 ScriptingExample2 . . . . . . . . . . . . . . . 23
2.8.4 Differentwaysofimportingmodules . . . . . . 24
2.9 GettingHelp:DocumentationinIPython . . . . . . . 26
vii
viii Contents
2.10 Stand-aloneIPython . . . . . . . . . . . . . . . . . . . 26
2.10.1 WritingPythonscriptsinatexteditor . . . . . 27
2.11 ProgrammingErrors . . . . . . . . . . . . . . . . . . . 28
2.11.1 Pyflakes . . . . . . . . . . . . . . . . . . . . . . 28
2.11.2 Errorchecking . . . . . . . . . . . . . . . . . . . 29
2.12 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3 Strings,Lists,Arrays,andDictionaries 33
3.1 Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.2 Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.2.1 Slicinglists . . . . . . . . . . . . . . . . . . . . . 37
3.2.2 Therangefunction:Sequencesofnumbers . . . 38
3.2.3 Tuples . . . . . . . . . . . . . . . . . . . . . . . 39
3.2.4 Multidimensionallistsandtuples . . . . . . . . 40
3.3 NumPyArrays . . . . . . . . . . . . . . . . . . . . . . . 41
3.3.1 Creatingarrays(1-d) . . . . . . . . . . . . . . . 41
3.3.2 Mathematicaloperationswitharrays . . . . . . 43
3.3.3 Slicingandaddressingarrays . . . . . . . . . . 46
3.3.4 Fancyindexing:Booleanmasks . . . . . . . . . 47
3.3.5 Multi-dimensionalarraysandmatrices . . . . . 49
3.3.6 Differencesbetweenlistsandarrays . . . . . . 52
3.4 Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . 53
3.5 Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.6 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4 InputandOutput 61
4.1 KeyboardInput . . . . . . . . . . . . . . . . . . . . . . 61
4.2 ScreenOutput . . . . . . . . . . . . . . . . . . . . . . . 64
4.2.1 Formattingoutputwithstr.format() . . . . . 64
4.2.2 Printingarrays . . . . . . . . . . . . . . . . . . . 68
4.3 FileInput . . . . . . . . . . . . . . . . . . . . . . . . . 69
4.3.1 Readingdatafromatextfile . . . . . . . . . . . 69
4.3.2 ReadingdatafromanExcelfile:CSVfiles . . . 71
4.4 FileOutput . . . . . . . . . . . . . . . . . . . . . . . . 73
4.4.1 Writingdatatoatextfile . . . . . . . . . . . . . 73
4.4.2 WritingdatatoaCSVfile . . . . . . . . . . . . 76
4.5 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Contents ix
5 ConditionalsandLoops 81
5.1 Conditionals . . . . . . . . . . . . . . . . . . . . . . . . 82
5.1.1 if,elif,andelsestatements . . . . . . . . . . 82
5.1.2 Logicaloperators . . . . . . . . . . . . . . . . . 86
5.2 Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
5.2.1 forloops . . . . . . . . . . . . . . . . . . . . . . 87
5.2.2 whileloops . . . . . . . . . . . . . . . . . . . . . 91
5.2.3 Loopsandarrayoperations . . . . . . . . . . . 93
5.3 ListComprehensions . . . . . . . . . . . . . . . . . . . 94
5.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . 96
6 Plotting 99
6.1 AnInteractiveSessionwithPyPlot . . . . . . . . . . . 100
6.2 BasicPlotting . . . . . . . . . . . . . . . . . . . . . . . 102
6.2.1 Specifyinglineandsymboltypesandcolors . . 106
6.2.2 Errorbars . . . . . . . . . . . . . . . . . . . . . 108
6.2.3 Settingplottinglimitsandexcludingdata . . . 110
6.2.4 Subplots . . . . . . . . . . . . . . . . . . . . . . 113
6.3 LogarithmicPlots . . . . . . . . . . . . . . . . . . . . . 116
6.3.1 Semi-logplots . . . . . . . . . . . . . . . . . . . 116
6.3.2 Log-logplots . . . . . . . . . . . . . . . . . . . . 118
6.4 MoreAdvancedGraphicalOutput . . . . . . . . . . . 118
6.4.1 Analternativesyntaxforagridofplots . . . . 122
6.5 Plotswithmultipleaxes . . . . . . . . . . . . . . . . . 125
6.6 MathematicsandGreeksymbols . . . . . . . . . . . . 126
6.7 TheStructureofmatplotlib:OOPandAllThat . . . . 131
6.7.1 Thebackendlayer . . . . . . . . . . . . . . . . . 132
6.7.2 Theartistlayer. . . . . . . . . . . . . . . . . . . 135
6.7.3 ThePyPlot(scripting)layer . . . . . . . . . . . 137
6.8 ContourandVectorFieldPlots . . . . . . . . . . . . . 139
6.8.1 Makinga2Dgridofpoints . . . . . . . . . . . . 139
6.8.2 Contourplots . . . . . . . . . . . . . . . . . . . 140
6.8.3 Streamlineplots . . . . . . . . . . . . . . . . . . 144
6.9 Three-DimensionalPlots . . . . . . . . . . . . . . . . . 149
6.10 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . 152
7 Functions 155
7.1 User-DefinedFunctions . . . . . . . . . . . . . . . . . 156
7.1.1 Loopingoverarraysinuser-definedfunctions . 158