I have a layer with line segments and a layer of polygons (in this case, buffers around points). I need to create a new field for each polygon that contains the total length of all line segments contained within that polygon, including portions of the line segments with the polygon that straddle the borders.
A slight modification of the answer linked in the comments would be to do a Summary Statistics to get the SUM of the
Shape.Length field of the intersect feature class, using the FID field of the polygons a case field, and then Join Field that back to the polygon feature class.
In the ArcMap 10.1 Python window, these commands worked for me:
intersection = arcpy.Intersect_analysis("RoadCenterline;SchoolTaxDistrict", r"in_memory\intersect") arcpy.CalculateField_management(intersection, "SHAPE_Leng", "!shape.length!", "PYTHON_9.3") summary = arcpy.Statistics_analysis(intersection, r"in_memory\statistics", "SHAPE_Leng SUM", "FID_SchoolTaxDistrict") arcpy.JoinField_management("SchoolTaxDistrict", "FID", summary, "FID_SchoolTaxDistrict")