[Tutor] Creating a Polyline Feature class

[bob gailer]

On 3/3/2012 11:21 PM, Carie Pigeon wrote:
> I have an assignment to create a polyline feature class of rhino 
> tracks from a csv file.  I am getting an error that says "unbound 
> method add() must be called with Array instance as first argument (got 
> type instance)".  this is for line 104, the line I underlined and put 
> in bold below in my code.  What does this mean?  If there are other 
> obvious code issues, please feel free to comment.  I am unsure if my 
> code is correct.  Thank you for your time!
> Cheers,
> Carie
>
> # Reads rhino positions from an Excel-originating CSV file
>
> import arcpy
> from arcpy import env
> import fileinput
> import string
> import os
>
> env.overwriteOutput = True
>
> # Hard code file paths
> spreadsheet = "C:/WCGIS/Geog485/Lesson4/
> RhinoObservations.csv"
>
> # Sample of data
> ###Observer,X,Y,Rhino,Comments
> ##Ben,26.99391,-19.10447,Bo,
> ##Ben,27.00071,-19.1089,Tulip,Bathing
> ##Ben,26.9919,-19.10511,Bo,
> ##Ben,27.00071,-19.1059,Tulip,
> ##Ben,26.96809,-19.09578,Patches,
> ##Ben,26.97808,-19.11016,Dinky,
> ##Ben,26.99213,-19.10395,Bo,
> ##Ben,27.00083,-19.10326,Tulip,
> ##Ben,26.97038,-19.09863,Patches,Not doing much of anything
> ##Ben,26.97768,-19.11153,Dinky,
> ##Ben,26.99107,-19.10421,Bo,
> ##Ben,27.00138,-19.1021,Tulip,
> ##Ben,26.97122,-19.0991,Patches,
> ##Ben,26.97551,-19.11269,Dinky,
> ##Ben,26.9904,-19.10553,Bo,
> ##Ben,26.99893,-19.10342,Tulip,
>
> # output feature class??  feature class doesn't exist yet, so not sure 
> how to do this??
> fcname = "C:/WCGIS/Geog485/Lesson4"
> outname = "C:/WCGIS/Geog485/Lesson4/Rhino.shp"
>
>
>
> # Open the CSV file & read the header line
> observations = open(spreadsheet, "r")
> headerline = observations.readline()
> fieldList = headerline.split(",")
>
> ###     0    1 2   3      4
> ### Observer,X,Y,Rhino,Comments
> # Look through the header to find "X", "Y" and the "Rhino" field indices
> rhinoIndex = fieldList.index("Rhino")
> xIndex = fieldList.index("X")
> yIndex = fieldList.index("Y")
> ## print "Rhino "+str(rhinoIndex) +" X "+str(xIndex)+" Y "+str(yIndex)
>
> # Create a list / array for RhinoTracks
> rhinoTracks = {}
>
> # create the output feature class
> arcpy.CreateFeatureclass_management ("C:/WCGIS/Geog485/Lesson4", 
> "Rhino.shp", "POLYLINE")
>
> # open an insert cursor for the new feature class
> cur = arcpy.InsertCursor(outname)
>
> # Loop through the rest of the file to read in all of the rhinos
> for line in observations.readlines():
>     ##Ben,26.99391,-19.10447,Bo,
>     segmentedLine = line.split(",")
>     rhino = segmentedLine[rhinoIndex]
>     #print rhino
>     # If rhino exists in dictionary - get the array from its key & add 
> a point
>     if rhino in rhinoTracks:
>         coordArray = rhinoTracks[rhino]
>         # create a new row or feature, in the feature class
>
>
>         ## coordArray { [x,y] }
>         lineArray = arcpy.Array()
>         coord = arcpy.Point
I am making educated guesses - try coord = arcpy.Point()
>         coord.X = segmentedLine[xIndex]
>         coord.Y = segmentedLine[yIndex]
>         ## add point to coordinate array
>         coordArray.add(coord)
>         #print "Rhino is "+rhino+" added point 
> "+str(segmentedLine[xIndex])+" "+str(segmentedLine[yIndex])
>         ## coordArray { [x,y],[x1,y1] }
>
>         feat = cur.newRow()
>
>         # set the geometry of the new feature to the array of points
>         feat.shape = lineArray
>
>         #insert the feature
>         cur.insertRow(feat)
>         lineArray.removeAll()
>         lineArray.add(coord)
>
>     # If rhino doesn't exist in dictionary - make a new array & add a 
> point
>     else:
>
>         cur = arcpy.InsertCursor(outname)
>         ## Create a coordinate array
>         coordArray = arcpy.Array
try coordArray = arcpy.Array()
>         ## Create a point object
>         coord = arcpy.Point
also try coord = arcpy.Point()
>         coord.X = segmentedLine[xIndex]
>         coord.Y = segmentedLine[yIndex]
>         ## add point to coordinate array
> *_coordArray.add(coord)
>
> _*        feat = cur.newRow()
>
>         # set the geometry of the new feature to the array of points
>         feat.shape = lineArray
>
>         #insert the feature
>         cur.insertRow(feat)
>         lineArray.removeAll()
>         lineArray.add(coord)
>         ## add coordinate array to my Dictionary (list of rhinos)
>         rhinoTracks[rhino] = coordArray
Do you understand the difference between
coord = arcpy.Point
and
coord = arcpy.Point()
?

The first gets you a reference to the class.
The 2nd gets you an instance of the class.
Quite different.

-- 
Bob Gailer
919-636-4239
Chapel Hill NC

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