ArcPy and ArcGIS – Geospatial Analysis with Python

Silas Toms

• Verlag: Packt Publishing
• Jahr: 2015
• ISBN:
  9781783988679
• Thema: Ciencia de la computación
• Thema: Servicios web y API

About This Book

• Perform GIS analysis faster by automating tasks, such as selecting data or buffering data, by accessing GIS tools using scripting
• Access the spatial data contained within shapefiles and geodatabases, for updates, analysis and even transformation between spatial reference systems
• Produce map books and automate the mapping of geospatial analyses, reducing the time needed to produce and display the results

Who This Book Is For

If you are a GIS student or professional who needs an understanding of how to use ArcPy to reduce repetitive tasks and perform analysis faster, this book is for you. It is also a valuable book for Python programmers who want to understand how to automate geospatial analyses.

ArcPy and ArcGIS – Geospatial Analysis with Python

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Table of Contents

ArcPy and ArcGIS – Geospatial Analysis with Python

Credits

About the Author

About the Reviewers

www.PacktPub.com

Support files, eBooks, discount offers, and more

Why subscribe?

Free access for Packt account holders

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Downloading the color images of this book

Errata

Piracy

Questions

1. Introduction to Python for ArcGIS

Overview of Python

Python as a programming language

Interpreted language

Standard (built-in) library

The glue language

Wrapper modules

The basics of Python

Import statements

Variables

For loops

If/Elif/Else statements

While statements

Comments

Data types

Strings

Integers

Floats

Lists

Tuples

Dictionaries

Iterable data types

Other important concepts

Indentation

Functions

Keywords

Namespaces

Zero-based indexing

Important Python Modules for GIS Analysis

The ArcPy module

The Operating System (OS) module

The Python System (SYS) module

The XLRD and XLWT modules

Commonly used built-in functions

Commonly used standard library modules

Summary

2. Configuring the Python Environment

What is a Python script?

How Python executes a script

What is the Python interpreter?

Where is the Python interpreter located?

Which Python interpreter should be used?

How does the computer know where the interpreter is?

Make Python scripts executable when clicked on

Integrated Development Environments (IDEs)

IDLE

PythonWin

Aptana Studio 3

IDE summary

Python folder structure

Where modules reside

Using Python's sys module to add a module

The sys.path.append() method

Summary

3. Creating the First Python Script

Prerequisites

ModelBuilder

Creating a model and exporting to Python

Modeling the Select and Buffer tools

Adding the Intersect tool

Tallying the analysis results

Exporting the model and adjusting the script

The automatically generated script

File paths in Python

Continuing the script analysis: the ArcPy tools

The Intersect tool and string manipulation

The string manipulation method 1–string addition

The string manipulation method 2–string formatting #1

The string manipulation method 3–string formatting #2

Adjusting the Script

Adding the CSV module to the script

Accessing the data: Using a cursor

The final script

Summary

4. Complex ArcPy Scripts and Generalizing Functions

Python functions–Avoid repeating code

Technical definition of functions

A first function

Functions with parameters

Using functions to replace repetitive code

More generalization of the functions

Summary

5. ArcPy Cursors – Search, Insert, and Update

The data access module

Attribute field interactions

Update cursors

Updating the shape field

Adjusting a point location

Deleting a row using an Update Cursor

Using an Insert Cursor

Inserting a polyline geometry

Inserting a polygon geometry

Summary

6. Working with ArcPy Geometry Objects

ArcPy geometry object classes

ArcPy Point objects

ArcPy Array objects

ArcPy Polyline objects

ArcPy Polygon objects

Polygon object buffers

Other Polygon object methods

ArcPy geometry objects

ArcPy PointGeometry objects

Summary

7. Creating a Script Tool

Adding dynamic parameters to a script

Displaying script messages using arcpy.AddMessage

Adding dynamic components to the script

Creating a Script tool

Labelling and defining parameters

Adding data types

Adding the Bus Stop feature class as a parameter

Adding the Census Block feature class as a parameter

Adding the Census Block field as a parameter

Adding the output spreadsheet as a parameter

Adding the spreadsheet field names as a parameter

Adding the SQL Statement as a parameter

Adding the bus stop fields as a parameter

Inspecting the final script

Running the Script Tool

Summary

8. Introduction to ArcPy.Mapping

Using ArcPy with map documents

Inspecting and replacing layer sources

Fixing the broken links

Fixing the links of individual layers

Exporting to PDF from an MXD

Adjusting map document elements

Automated map document adjustment

The variables

The map document object and the text elements

The layer objects

Replacing the data sources

Adjusting layer visibility

Generating a buffer from the bus stops feature class

Intersecting the bus stop buffer and census blocks

Populating the selected bus stop and buffer feature classes

Updating the text elements

Exporting the adjusted map to PDF

Running the script in the Python Window

Summary

9. More ArcPy.Mapping Techniques

Using arcpy.mapping to control Layer objects

Layer object methods and properties

Definition queries

Controlling the data frame window extent and scale

Adding a Layer object

Exporting the maps

Summary

10. Advanced Geometry Object Methods

Creating a Python module

The __init__.py file

Adding advanced analysis components

Advanced Polygon object methods

Generating random points to represent population

Using the functions within a script

Creating an XLS using XLWT

Summary

11. Network Analyst and Spatial Analyst with ArcPy

The Network Analyst extension

Using Network Analyst

Creating a Feature Dataset

Importing the datasets

Creating the Network Dataset

Accessing the Network Dataset using ArcPy

Breaking down the script

The Network Analyst module

Accessing the Spatial Analyst Extension

Adding elevation to the bus stops

Using Map Algebra to generate elevation in feet

Adding in the bus stops and getting elevation values

The final result

Summary

12. The End of the Beginning

Getting field information from feature classes

Accessing the ListFields' properties

List comprehensions

Creating the field information functions

Querying feature class information

Generating File Geodatabases and feature classes

Generating a feature class

Setting up the script tool parameters

Environmental settings

Resolution and tolerance settings

Summary

Index

ArcP...