topic Points to Lines in Geoprocessing Questions

Points to Lines

neilwebster — Mon, 19 Apr 2010 08:22:16 GMT

Hi All,

I have a dbf file with from and to points. I'm trying to use the python examples to generate a polyline but it is defeating me!

The script I have been using is below. Whenever it is run it generates one visible line and creates attribute table entries for the other rows in the input table.

Can anybody suggest what is going wrong?

Cheers, Neil.

Code (the indentation might not be correct on the posting):

import sys, string, os, arcgisscripting
gp = arcgisscripting.create(9.3)
gp.OverWriteOutput = True

Out = r"C:\Test_Out.shp"
In = r"C:\In.dbf"

gp.workspace = os.path.dirname(Out)
gp.CreateFeatureclass(os.path.dirname(Out), os.path.basename(Out), "POLYLINE")

cur = gp.InsertCursor (Out)
Searchrows = gp.SearchCursor(In)
Searchrow = Searchrows.Next()
while Searchrow:
row = cur.NewRow()

LineArray = gp.CreateObject("Array")
pnt = gp.CreateObject ("Point")

pnt.x = Searchrow.GetValue("From_Lon")
pnt.y = Searchrow.GetValue("From_Lat")
LineArray.add(pnt)

pnt.x = Searchrow.GetValue("To_Lon")
pnt.y = Searchrow.GetValue("To_Lat")
LineArray.add(pnt)

print Searchrow.GetValue("To_Lon"), Searchrow.GetValue("To_Lat")
row.shape = LineArray
cur.InsertRow(row)

Searchrow = Searchrows.Next()

del row, cur

Points to Lines

BradPosthumus — Mon, 19 Apr 2010 15:46:35 GMT

I tested this script and it produced the lines expected, using a test dbf. When you run it, are you getting multiple copies of the same line? What values are you getting for from this print statement:

print Searchrow.GetValue("To_Lon"), Searchrow.GetValue("To_Lat")

Points to Lines

neilwebster — Tue, 20 Apr 2010 06:36:25 GMT

Thanks for the reply.

The line mentioned outputs the cordinates of the to nodes, as per the input file.

However no line is created. The only line created is for the first line of the input file.

Any ideas

Points to Lines

JonathanBaarda — Tue, 20 Apr 2010 16:37:06 GMT

I just tried your code myself on a test dbf and got the right output. I would take a look at your test file. Maybe the points are identical?

Points to Lines

Jan_ToreKyrdalen — Sat, 11 Dec 2021 10:46:18 GMT

Dont you allso need to give the points an id?

changing:

pnt.x = Searchrow.GetValue("From_Lon")
pnt.y = Searchrow.GetValue("From_Lat")
LineArray.add(pnt)

pnt.x = Searchrow.GetValue("To_Lon")
pnt.y = Searchrow.GetValue("To_Lat")
LineArray.add(pnt)

to:

pnt.id = some_counter
pnt.x = Searchrow.GetValue("From_Lon")
pnt.y = Searchrow.GetValue("From_Lat")
LineArray.add(pnt)

pnt.id = some_counter
pnt.x = Searchrow.GetValue("To_Lon")
pnt.y = Searchrow.GetValue("To_Lat")
LineArray.add(pnt)