Obtaining extent of each polygon in shapefile using ArcPy?

In ArcGIS 10 and Python I want to get the extent (xmax, ymax, xmin, ymin) info of each of the polygons in a shapefile.

I can get the extent of the whole shapefile using

file=r"D:SCRATCHARCGIS100k_trc_tiles_TVM.shp"
desc=arcpy.Describe(file)
print desc.extent.Xmax

394551.52085039532

But I can’t seem to figure out how to get the same info for each row in the dataset.

rows = arcpy.SearchCursor("100k_trc_tiles_TVM")
for row in rows:
 print row

prints the 31 rows in the dataset but

for row in rows:
 desc=arcpy.Describe(row)
 print desc.extent.Xmax

gives an error.

Runtime error : Object: Describe input
value is not valid type

I was thinking of adding the extent values to the table using “calculate geometry” but this only gives the centroid. Then I guess we can use something like row.GetValue(“xmax”).

That being said I know that we can create the X/Y, max/min using the function from http://www.ian-ko.com/free/free_arcgis.htm but it would be best if we can avoid having to add fields, especially if ArcPy can get these values.

Basically I need to get the extents to feed into the clip tool to clip out 30 areas of data (according to the 1:100,000 map sheets) for geoprocessing since the Split tool fails due to the large size of the dataset (see Why Intersect gives ERROR 999999: Error executing function Invalid Topology [Too many lineseg endpoints]?). I want to automate this as it is repeated on a number of datasets.

=== working script ===

# Emulates Arc Info SPLIT tool by using Clip but
# Requires a FC from which each row is used as the input clip feature.
# Each row must be rectangular.
# Used on 12GB FGDB with 100 million records.


#Licence: Creative Commons
#Created by: George Corea; [email protected], [email protected]
import arcpy, string

#inFrame=arcpy.GetParameterAsText(0) # Input dataframe FC
#inFile=arcpy.GetParameterAsText(1) # Input FC for splitting
#outDir=arcpy.GetParameterAsText(2) # Output FGDB

inFrame=r"D:SCRATCHARCGIS100k_trc_tiles_TVM.shp"
inFile=r"c:junk106data7_Merge.gdbFullRez_m2b"
outDir=r"D:SCRATCHProjects206datasplittest_slaasp.gdb"
#NameField="Name_1"

#arcpy.env.workspace = r"C:/Workspace"
arcpy.env.overwriteOutput = True

rows = arcpy.SearchCursor(inFrame)
shapeName = arcpy.Describe(inFrame).shapeFieldName
for row in rows:
    feat = row.getValue(shapeName)
    Name = row.Name_1
    print "Executing clip on: "+str(Name)
    extent = feat.extent
    #print extent.XMin,extent.YMin,extent.XMax,extent.YMax
# Create an in_memory polygon
    XMAX = extent.XMax
    XMIN = extent.XMin
    YMAX = extent.YMax
    YMIN = extent.YMin
    pnt1 = arcpy.Point(XMIN, YMIN)
    pnt2 = arcpy.Point(XMIN, YMAX)
    pnt3 = arcpy.Point(XMAX, YMAX)
    pnt4 = arcpy.Point(XMAX, YMIN)
    array = arcpy.Array()
    array.add(pnt1)
    array.add(pnt2)
    array.add(pnt3)
    array.add(pnt4)
    array.add(pnt1)
    polygon = arcpy.Polygon(array)
    ShapeFile = outDir+"temp_poly"
    arcpy.CopyFeatures_management(polygon, ShapeFile)

    #print Name
### Set local variables
    in_features = inFile
    clip_features = ShapeFile
    out_feature_class = outDir+""+Name
    xy_tolerance = "0.22"

    # Execute Clip

    try:
        arcpy.Clip_analysis(in_features, clip_features, out_feature_class, xy_tolerance)
        print "Completed: "+str(Name)
    except:
        error = arcpy.GetMessages()
        print "Failed on: "+str(Name)+" due to "+str(error)

shapeName = arcpy.Describe(inFeatures).shapeFieldName
for row in rows:
    feat = row.getValue(shapeName)
    extent = feat.extent
    print extent.XMin,extent.YMin,extent.XMax,extent.YMax

print desc.extent.XMax

print desc.extent.Xmax

rows = arcpy.SearchCursor(shapefileName)

for row in rows:
   extent = row.shape.extent
   ...
   ...