Working with geometry in Python

All simple feature classes require a geometry field, typically (but not always) named Shape. The Describe function can be used to retrieve the name of geometry field from a feature class, using the shapeFieldName property. The value of the geometry field is a geometry object, and a geometry object has a number of properties that describe the feature. The example below shows how to create a geometry object for each line feature in a feature class and sum their length:

Reading_geometriesWriting_geometries

import arcpy

inFeatures = "d:/base/data.gdb/roads"

# Create search cursor
#
rows = arcpy.SearchCursor(inFeatures)

# Calculate the total length of all roads
#
length = 0

shapeName = arcpy.Describe(inFeatures).shapeFieldName

# For each row, tally the length of the feature
#
for row in rows:
    feat = row.getValue(shapeName)
    length += feat.length

# Print the total length of all roads
#
print length

Property	Explanation
area	The area of a polygon; empty for all other feature types
centroid	The true centroid if it is within or on the feature; otherwise, returns the label point (returns a point object)
extent	Returns an extent object
firstPoint	The first coordinate of the feature; returns a point object
hullRectangle	The coordinate pairs of the convex hull rectangle
isMultipart	True, if the number of parts for this geometry is more than one
labelPoint	The point at which the label is located; returns a point object (The labelPoint is always located within or on a feature.
lastPoint	The last coordinate of the feature; returns a point object
length	The length of the linear feature; empty for point, multipoint feature types
partCount	The number of geometry parts for the feature
pointCount	The number of point objects for the current part of geometry
trueCentroid	The center of gravity for a feature; returns a point object
type	Polygon, polyline, point, multipoint, multipatch, dimension, annotation

Geometry properties

Method	Explanation
getPart({index})	Returns an array of point objects for a particular part of geometry or an array containing a number of arrays, one for each part

Geometry methods