Using Python in ArcGIS 10, create a line between the middle of the lines

Alper_Sen

I have got a river network as a feature class in a gdb.

I need to calculate the topologic attributes via the connectivity graph of the river network. A graph-theoretic representation of river networks uses rivers as vertices and river junctions as links of a connectivity graph to understand the topology of river network (takes rivers as nodes and river intersections as links of a connectivity graph). It will give information about centrality of lines and also simplify the network.

In order to do this, I want to draw lines from the middle of each river branch to the middle of intersected higher order river. By this way, I can calculate the topological centrality of a river branch by using from-to node information.

When doing this manually, I draw a polyline from the middle of a river line to the middle of intersected higher order river line. Please help me to do this automatically by using Python in ArcGIS 10. If I do it manually it will take too long because of the drainage density.
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river.jpg

Dirk_Vandervoort_0-1746121889558.png

JakeSkinner

Here is an example on how to do this:

import arcpy from arcpy import env env.workspace = r"C:\TEMP\Python\test.gdb" env.overwriteOutput = 1  fc1 = "River" fc2 = "New_Poyline"  coordList = []  arcpy.FeatureVerticesToPoints_management(fc1, "vertices", "MID") arcpy.AddXY_management("vertices") rows = arcpy.SearchCursor("vertices") for row in rows:     X = row.getValue("POINT_X")     Y = row.getValue("POINT_Y")     coordList.append([X, Y])  del row, rows  coordList.sort()  point = arcpy.Point() array = arcpy.Array()  for feature in coordList:     point.X = feature[0]     point.Y = feature[1]     array.add(point)  polyline = arcpy.Polyline(array)      array.removeAll() arcpy.Delete_management("vertices") arcpy.CopyFeatures_management(polyline, fc2)

This will create a polyline feature class using the midpoint vertices of each River segment.  It starts from the lowest mid-point and ends at the highest.