Take the 2-minute tour ×
Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. It's 100% free, no registration required.

My objective is to swap X,Y coordinates of feature classes using Python and arcgisscripting. Based on help examples, I managed to write script which reads and writes all geometry types.

The problem is with polyline geometry: for multipart lines, all parts are connected and they should be disjoint. It seems that connection between last vertex of one part is connected with first vertex of next part.
It's strange especially as script deals well with multipart polygons and polygons with void.

Am I missing something with multipart polyline geometry?

import arcgisscripting
gp = arcgisscripting.create(9.3)

gp.overwriteoutput = True
gp.workspace = r"D:\Work\SwapXY.gdb"
inFC = r"D:\Work\SwapXY.gdb\Line"

desc = gp.Describe(inFC)
shapeField = desc.ShapeFieldName  #SHAPE field name
shapeType = desc.ShapeType

# Create FC for inserting swaped geometries (if not exist)
...

try:
    rows = gp.SearchCursor(inFC) #open SearchCursor on input FC
    row = rows.next()
    outRows = gp.InsertCursor(outFC) #open InsertCursor on output FC

    #create Array object which will contain features vertices (other than points)
    vertexArray = gp.CreateObject("Array")

    while row:
        feature = row.getValue(shapeField) #get the SHAPE field into variable

        ##For point geometry there is another way of reading coordinates than for polyline/polygon
        if shapeType.upper() == "POINT" or shapeType.upper() == "MULTIPOINT":
           #this part works right

        else:
            #feature can have multiple parts - first goes iteration through parts
            partNum = 0
            partCount = feature.PartCount
            while partNum < partCount:
                part = feature.GetPart(partNum) #the output is Array of points
                pnt = part.next() #take first point from Array of points

                #iterate through all points in array
                while pnt:
                    #for each geometry create new POINT obj and assign swapped Y, X. Then add vertices to ARRAY
                    vertex = gp.CreateObject("Point")
                    vertex.X = pnt.Y
                    vertex.Y = pnt.X
                    vertexArray.add(vertex)
                    pnt = part.next()

                    #If pnt is null, either the part is finished or there is an interior ring
                    if not pnt:
                        pnt = part.next()
                        if pnt:
                            print "Interior:"

                partNum += 1

            newFeature = outRows.newRow()
            newFeature.shape = vertexArray       #assign ARRAY filled with points to shape field
            outRows.insertRow(newFeature)              

            vertexArray.RemoveAll() #clear ARRAY before processing new geometry

        row = rows.next()
except:
    print gp.GetMessages()

EDIT: In fact script doesn't work for polygons with more than one interior ring. So the problem is wider than I thought.
In polygon case, I've found that null point between exterior and interior rings should be inserted. But when gp.CreateObject("Point") is inserted, a point with coordinates (0,0) is added.

share|improve this question

1 Answer 1

up vote 2 down vote accepted

As adding null point as it was suggested here gave a point with (0,0) cordinates, I searched existing scripts in ESRI repository and I've found another way of separating polygon rings as well as polyline parts.
The solution is based on creating two arrays: featureVertexArray for storing whole geometry and partVertexArray for storing separate rings:

try:
    rows = gp.SearchCursor(inFC) #open SearchCursor on input FC
    row = rows.next()
    outRows = gp.InsertCursor(outFC) #open InsertCursor on output FC

    #create Array object which will contain features vertices
    featureVertexArray = gp.CreateObject("Array")
    partVertexArray = gp.CreateObject("Array")

    while row:
        feature = row.getValue(shapeField) #get the SHAPE field into variable
        vertex = gp.CreateObject("Point") #empty Point object to store geometry

        ##For point geometry there is another way of reading coordinates than for polyline/polygon
        if shapeType.upper() == "POINT" or shapeType.upper() == "MULTIPOINT":
            #this part works right

        else:
            #feature can have multiple parts - first goes iteration through parts
            partNum = 0
            partCount = feature.PartCount
            while partNum < partCount:
                part = feature.GetPart(partNum) #the output is Array of points
                pnt = part.next() #take first point from Array of points

                #iterate through all points in array
                while pnt:
                    #for each geometry create new POINT obj and assign swapped Y, X. Then add vertices to ARRAY
                    vertex.X, vertex.Y = pnt.Y, pnt.X
                    partVertexArray.add(vertex)
                    pnt = part.next()

                    #If pnt is null, either the part is finished or there is an interior ring
                    if not pnt:
                        pnt = part.next()
                        featureVertexArray.add(partVertexArray)
                        partVertexArray.removeAll()
                        #if pnt:
                            #print "Interior:"

                featureVertexArray.add(partVertexArray)
                partNum += 1 #increment part number to run loop

            newFeature = outRows.newRow()   #create new row in InsCur
            newFeature.shape = featureVertexArray       #assign ARRAY filled with points to shape field
            outRows.insertRow(newFeature)   #insert new row                

        featureVertexArray.removeAll() #clear ARRAYS before processing new geometry
        partVertexArray.removeAll()

        row = rows.next()
share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.