Book Image

Programming ArcGIS 10.1 with Python Cookbook

By : Donald Eric Pimpler, Eric Pimpler
Book Image

Programming ArcGIS 10.1 with Python Cookbook

By: Donald Eric Pimpler, Eric Pimpler

Overview of this book

ArcGIS is an industry standard geographic information system from ESRI.This book will show you how to use the Python programming language to create geoprocessing scripts, tools, and shortcuts for the ArcGIS Desktop environment.This book will make you a more effective and efficient GIS professional by showing you how to use the Python programming language with ArcGIS Desktop to automate geoprocessing tasks, manage map documents and layers, find and fix broken data links, edit data in feature classes and tables, and much more."Programming ArcGIS 10.1 with Python Cookbook" starts by covering fundamental Python programming concepts in an ArcGIS Desktop context. Using a how-to instruction style you'll then learn how to use Python to automate common important ArcGIS geoprocessing tasks.In this book you will also cover specific ArcGIS scripting topics which will help save you time and effort when working with ArcGIS. Topics include managing map document files, automating map production and printing, finding and fixing broken data sources, creating custom geoprocessing tools, and working with feature classes and tables, among others.In "Python ArcGIS 10.1 Programming Cookbook" you'll learn how to write geoprocessing scripts using a pragmatic approach designed around an approach of accomplishing specific tasks in a Cookbook style format.

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Programming ArcGIS 10.1 with Python Cookbook
Donald Eric Pimpler | Eric Pimpler
Feb, 2013 | 304 pages
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Table of Contents (21 chapters)
Programming ArcGIS 10.1 with Python Cookbook
Programming ArcGIS 10.1 with Python Cookbook
Credits
Credits
About the Author
About the Author
About the Reviewers
About the Reviewers
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
Fundamentals of the Python Language for ArcGIS
Fundamentals of the Python Language for ArcGIS
Using IDLE for Python script development
Python language fundamentals
Summary
2
Writing Basic Geoprocessing Scripts with ArcPy
Writing Basic Geoprocessing Scripts with ArcPy
Introduction
Using the ArcGIS Python window
Accessing ArcPy with Python
Executing tools from a script
Using ArcGIS Desktop help
Using variables to store data
Accessing ArcPy modules with Python
3
Managing Map Documents and Layers
Managing Map Documents and Layers
Introduction
Referencing the current map document
Referencing map documents on a disk
Accessing a data frame
Getting a list of layers in a map document
Restricting the list of layers
Changing the map extent
Getting a list of tables
Adding layers to a map document
Inserting layers into a map document
Updating layer symbology
Updating layer properties
4
Finding and Fixing Broken Data Links
Finding and Fixing Broken Data Links
Introduction
Finding broken data sources in your map document and layer files
Fixing broken data sources with MapDocument.findAndReplaceWorkspacePaths()
Fixing broken data sources with MapDocument.replaceWorkspaces()
Fixing individual Layer and Table objects with replaceDataSource()
Finding all broken data sources in all map documents in a folder
5
Automating Map Production and Printing
Automating Map Production and Printing
Introduction
Creating a list of layout elements
Assigning a unique name to layout elements
Restricting the layout elements returned by ListLayoutElements()
Updating layout element properties
Getting a list of available printers
Printing maps with PrintMap()
Exporting a map to a PDF file
Exporting a map to an image file
Creating a map book with PDFDocumentCreate() and PDFDocumentOpen()
6
Executing Geoprocessing Tools from Scripts
Executing Geoprocessing Tools from Scripts
Introduction
Finding geoprocessing tools
Retrieving a toolbox alias
Executing geoprocessing tools from a script
Using the output of a tool as an input to another tool
Setting environment variables and examining tool messages
7
Creating Custom Geoprocessing Tools
Creating Custom Geoprocessing Tools
Introduction
Creating a custom geoprocessing tool
8
Querying and Selecting Data
Querying and Selecting Data
Introduction
Constructing proper attribute query syntax
Creating feature layers and table views
Selecting features and rows with the Select Layer by Attribute tool
Selecting features with the Select by Location tool
Combining a spatial and attribute query with the Select by Location tool
9
Using the ArcPy Data Access Module to Select, Insert, and Update Geographic Data and Tables
Using the ArcPy Data Access Module to Select, Insert, and Update Geographic Data and Tables
Introduction
Retrieving features from a feature class with a SearchCursor
Filtering records with a where clause
Improving cursor performance with geometry tokens
Inserting rows with InsertCursor
Updating rows with an UpdateCursor
Deleting rows with an UpdateCursor
Inserting and updating rows inside an edit session
Reading geometry from a feature class
10
Listing and Describing GIS Data
Listing and Describing GIS Data
Introduction
Getting a list of feature classes in a workspace
Restricting the list of feature classes returned with a wildcard
Restricting the list of feature classes returned with a feature type.
Getting a list of fields in a feature class or table
Using the Describe() function to return descriptive information about a feature class
Using the Describe() function to return descriptive information about an image
Returning workspace information with the Describe() function
11
Customizing the ArcGIS Interface with Add-Ins
Customizing the ArcGIS Interface with Add-Ins
Introduction
Downloading and installing the Python Add-In wizard
Creating a button add-in
Installing and testing an add-in
Creating a tool add-in
12
Error Handling and Troubleshooting
Error Handling and Troubleshooting
Introduction
Exploring the default Python error message
Adding Python exception handling structures (try/except/finally)
Retrieving tool messages with GetMessages()
Filtering tool messages by severity level
Testing for and responding to specific error messages
Returning individual messages with GetMessage()
Automating Python Scripts
Automating Python Scripts
Introduction
Running Python scripts from the command line
Using sys.argv[ ] to capture command-line input
Adding Python scripts to batch files
Scheduling batch files to run at prescribed times
Five Things Every GIS Programmer Should Know How to Do with Python
Five Things Every GIS Programmer Should Know How to Do with Python
Introduction
Reading data from a delimited text file
Sending e-mails
Retrieving files from an FTP server
Creating ZIP files
Reading XML files
Index
Index

Scheduling batch files to run at prescribed times

Once created, your batch files can then be scheduled to run at prescribed times using the Windows Scheduler.

Getting ready

Many geoprocessing scripts are time-intensive and best run after hours when they can take full advantage of system resources and free up your time to concentrate on other tasks. In this recipe, you will learn how to use the Windows Scheduler to schedule the execution of your batch files.

How to do it...

Follow these steps to schedule a batch file with the Windows Scheduler:

  1. Open the Windows Scheduler by going to Start | Programs | Accessories | System Tools | Control Panel | Administrative Tools. Select Task Scheduler. The scheduler should appear, as shown in the following screenshot:

  2. Select the Action menu item and then Create Basic Task to display the Create Basic Task Wizard dialog box, as shown in the next screenshot.

  3. Give your task a name. In this case, we will call it List Fields from a Feature Class. Click on Next:

  4. Select a trigger for when the task should be executed. This can, and often will be, a time-based trigger, but there can also be other types of triggers such as a user login or computer start. In this case, let's just select Daily. Click on Next:

  5. Select a start date/time as well as a recurrence interval. In the following screenshot, I have selected the date as 12/3/2012, with time as 1:00:00 AM, and a recurrence interval of 1 day. So, every day at 1:00 AM, this task will be executed. Click on Next:

  6. Select Start a program as the action:

  7. Browse to your script and add the parameters. Click on Next:

  8. Click on Finish to add a task to the scheduler:

  9. The tasks should now be displayed in the list of active tasks:

How it works...

The Windows Task Scheduler keeps track of all the active tasks and handles the execution of these tasks when the prescribed trigger is fired. In this recipe, we have scheduled our task to execute each day at 1:00 AM. At that time, the batch file we created will be triggered and the arguments we specified when creating the task will be passed into the script. Using the scheduler to automatically execute geoprocessing tasks after hours without the need for GIS staff to interact with the scripts gives you more flexibility and increases your efficiency. You might also want to consider logging the errors in your Python scripts to a log file, for more information about specific problems.

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