Python Scripting in ArcGIS

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Python Scripting in ArcGIS

• Week 1
• Introduction and Model Builder Refresher

GEO 599, Fall 2009 Instructor Tracy Kugler
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Introductions

• Who am I?
• Geography PhD candidate
• GIS TA
• Needed Python for research
• Experience teaching myself programming languages
• Who are you?
• Field/research area
• Interest in Python/this course

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Purpose of the Course

• Become familiar with the Python scripting
  language as it relates to ArcGIS
• Be able to use Python to facilitate a variety of
  tasks in ArcGIS
• NOT a computer science course!

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Course Structure/Philosophy

• I provide framework, basic information and
  present problems
• Learn as much for yourself and from each other as
  from me
• Active lectures participation is expected
• Ask questions!
• New course let me know if something isnt
  working

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Logistics

• Exercises
• Start together, finish individually
• Submit via e-mail FOLLOW NAMING CONVENTIONS
• Late assignments -10 points/day let me know if
  time allowed is too short
• Resources
• Lack of good ArcGIS/Python text
• Online resources

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Computer Data Access

• Cordley 3003 lab
• Course meeting time
• Other non-scheduled times
• Digital Earth (Wilk 210) when not in use
• Data
• Download from course website
• http//people.oregonstate.edu/kuglert/
• Save to your ONID folder
• Work from your ONID folder

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Course Data

• Census geography
• Blocks ? Block groups ? Census tracts
• Hierarchy of geographical units over which
  statistics are agglomerated
• Urbanized areas
• Collections of (generally) contiguous,
  densely-settled block groups
• Metropolitan Statistical Areas
• Groups of counties
• Include a large population nucleus and
  surrounding communities associated with that
  nucleus

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Metropolitan Regions

• Based on MSA and UA
• Circular to standardize boundary shape
• Center is density-weighted center of UA within MSA

MSA
Region2
Region1
UA
Ctr
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Database Contents
3 Metro regions per dataset
4 datasets
2 tables
National UA feature class
8 Feature classes per metro region
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Pair and Compare

• Census Geography
• Metropolitan Regions

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Geoprocessing

• Organized sequence of steps to accomplish a
  spatial analysis task
• Examples of spatial analysis tasks?
• Process diagrams
• Pseudocode
• Standardized outcome of trial-and-error

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Model Builder

• Graphical method of doing geoprocessing
• Drag-and-drop data sets and tools
• Double-click on tools to set parameters
• Can export as Python script

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Model Builder Basics

• What are the inputs and outputs?
• What tools are used?
• What does this model do?

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Parameters in Models

• Setting model elements as parameters allows for
  user input
• Can mark inputs and outputs as parameters
• Can also create variables from tool parameters
• ArcGIS creates dialog box

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Model Properties

• General properties
• Name, Label
• Documentation
• Iteration set model to run multiple times

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ArcGIS Desktop Help

• Good resource make it your friend
• Help file for each ArcToolbox tool
• Describes, possibly illustrates, tools function
• Usage tips gives details, especially about input
  and output data types
• Includes section on Scripting Syntax