overview cursors arcpy.da module geometrys arrays spatialreferences licensing and installation

Overview

Cursors

arcpy.da module

Geometrys

Arrays

SpatialReferences

Licensing and Installation

arcpy.*Cursor functions

SearchCursor Syntax

SearchCursor Example

Update Cursor Syntax

Update cursor example

Insert Cursor Syntax

InsertCursor Example

Insert/Update and Locked data

Can not Insert/Update if data is lockedFeature class or table can be locked if it is:

Part of a map in an MXD that is open in ArcMapPart of a workspace being viewed by ArcCatalog

Best practices include:Exit ArcGIS applications when running scripts that create or modify tables or feature classesDelete cursor objects when you have finished using them …

The Data Access (da) module

arcpy.da.Walk( ) – an ArcGIS-aware version of os.path.walk ( )

New at 10.1

SearchCursor Function and Classarcpy Function

arcpy.da Class

SearchCursor Function and Class Example

262 sec for Function0.66 sec for Class~ 400 times faster in this case

Output:

arcpy.da.SearchCursor Class syntaxSearchCursor (in_table, field_names, {where_clause}, {spatial_reference}, {explode_to_points}, {sql_clause})

arcpy.SearchCursor Function syntaxSearchCursor (dataset, {where_clause}, {spatial_reference}, {fields}, {sort_fields})

The Geometry Class

Geometry Properties

Geometry Methods

… and clipcontainsconvexHullcrossesdifferencedisjointdistanceToequalsgetAreagetLengthgetPartintersectoverlapspositionAlongLineprojectAssymmetricDifferencetouchesunionwithin

Reading geometries

Writing geometries using Python

Problem: We have a text file containing a line identifier andx,y coordinates that we would like to use to createpolylines in an new feature class similar to an existing feature class

Solution:Create a script tool that has two inputs (text file name andtemplate feature class) and one output feature class.The script will - Create a new feature class based on the template feature class- Read the ID and coords for each line from the text file- Use an insert cursor to add each line to the new feature class

Before writing polylines to a feature class …

… need some other background

Polylines are created from an array of points

How is a point created?How is an array points created?

Point and PointGeometry Classes

PointGeometry Class

Array Class

Polyline

Writing geometries using Python

For Update/InsertCursor objects, test your scripts on a copy of the dataset. It is sometimes hard to undo modifications to data!

Input file structure:

Spatial reference and cursors

Creating a spatial reference

Licensing and Installation

Licensing and Installation

Check to see if a license is available

Returns license to license manager

Check out license from license manager

See if requested product is available

Information about installation

Install types that used with GetInstallInfo

Current product license

Legacy … replaced by