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Using Describe

Using Describe

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Using Describe

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  1. Using Describe

  2. Topics • How to use describe? • Retrieving Descriptive Information about data

  3. Describe( ) Function • Describe function returns a describe object containing a set of properties • Depending on what data type is being described, different describe properties will be available for use.

  4. Describe( ) Function • Describe on a FeatureClass returns a set of FeatureClass properties along with access to Table Properties and Dataset Properties That is using Describe() against a feature class not only provide access to a FeatureClass property group, but also a Table property group and a Dataset property group.

  5. Describe( ) Property Group Can explore each of them from ArcGIS online help!

  6. FeatureClass Properties • Commonly used FeatureClass properties • featureType Simple, Annotation, etc • shape Type Point, Polyline, Polygon, etc

  7. FeatureClass properties example import arcpy des = arcpy.Describe(“Auburn.gdb\\Parcel”) print “Feature Type: “ + des.featureType # returns Feature Type: Simple print “Shape Type: “ + des.shapeType # returns Shape Type: Polygon

  8. Table Properties This group contains a very useful propery • fields

  9. Field Object • Each field has a number of properties • The most common ones are -- name and -- type

  10. Field properties example import arcpy des = arcpy.Describe(“C:\\Data.gdb\\Parcel”) test = des.fields for field in test: print field.name print field.aliasName print field.type # returns LandUse Use String

  11. Dataset Properties • The dataset property group contains a number of useful properties • Commonly used properties are: - spatialReference - extent etc.

  12. Dataset Properties Example import arcpy file = "C:\\temp\\Data\\Schools.shp” des = arcpy.Describe(file) print des.spatialreference.name #Returns: NAD_1983_StatePlane_Texas_Central_FIPS_4203_Feet xyExtent= des.extent print "Xmin: " , xyExtent.XMin print "Xmax: " , xyExtent.XMax print "Ymin: " , xyExtent.YMin print "Ymax: " , xyExtent.YMax # returns: Xmin: 3037436.94 Xmax: 3220253.81 Ymin: 10006450.57 Ymax: 10164067.2

  13. Let’s try it!