topic Re: How do I flip X/Y geometry in a feature class? in Python Questions

How do I flip X/Y geometry in a feature class?

EricEagle — Mon, 17 Oct 2016 14:54:47 GMT

I have a geoJSON service I'm querying that's being supplied by GeoServer. I have a python script that ingests this feed routinely and uses arcpy.AsShape to render the geoJSON as various feature classes (I am extracting points, lines and polygons).

The problem is that the X/Ys in the service itself are backwards, even according to its own documentation. So my features are falling in all kinds of impossible locations.

Is there a fast way in python to flip the X/Y geometry in feature classes, including the vertices of line and polygon types?

Re: How do I flip X/Y geometry in a feature class?

DarrenWiens2 — Mon, 17 Oct 2016 17:19:11 GMT

I'm not aware of something like a "flip" geoprocessing tool, but you can do this using arcpy geometry objects and an Update Cursor.

Reading geometries—Help | ArcGIS for Desktop

Writing geometries—Help | ArcGIS for Desktop

Re: How do I flip X/Y geometry in a feature class?

JoshuaBixby — Mon, 17 Oct 2016 18:44:39 GMT

Is the service public? If so, it would be helpful to share a link.

Creating and manipulating geometries objects is more expensive than creating and manipulating native Python data types. Instead of using arcpy.AsShape() and then trying to flip X/Y, why not process the incoming GeoJSON service and do the flipping before passing to arcpy.AsShape() to create the geometry?

Re: How do I flip X/Y geometry in a feature class?

EricEagle — Mon, 17 Oct 2016 19:27:34 GMT

Joshua,

Unfortunately the service is not public. However I can give you an idea of the payload. It looks like this:

{

"type":"FeatureCollection",

"totalFeatures":4000000,

"features":

[

{

"type":"Feature",

"id":(guid here)

"geometry":

{

"type":"Point",

"coordinates":[10.0000000000,11.0000000000]

}

...

and for "LineString" type, it reads

"coordinates":[[10.0000000000,11.0000000000],[12.0000000000,13.0000000000],etc....]

So in every. single. list item, I need to swap the lat/lons.

I am barely getting out of novice python and am not very savvy when it comes to this. I am of course interested in doing this in the least costly way, so doing this prior to saving it as a series of feature classes is fine; I just figured there may be something very brief built into arcpy that might do this without much glue on an extant feature class.

If this is not the case I'm looking for help either with a snippet of code or even pseudocode to help me think through the mechanics.

It should be mentioned that currently I am ingesting this content as a .json file and then writing feature classes out of it. This content represents millions of rows, so I am not sure what would be quicker - opening an existing feature class, or re-writing the text document. Of course I am totally open to being shown better ways to do this!

Re: How do I flip X/Y geometry in a feature class?

JoshuaBixby — Mon, 17 Oct 2016 22:25:13 GMT

Before I dive into it any deeper, I want to understand how you are processing this GeoJSON information. Are you taking the JSON file and iterating over the feature collection and calling arcpy.AsShape() with each feature/geometry?

Re: How do I flip X/Y geometry in a feature class?

DanPatterson_Retired — Tue, 18 Oct 2016 00:02:10 GMT

for people trying to follow along

AsShape—Help | ArcGIS for Desktop

If the Esri JSON is a feature set, AsShape will return a FeatureSet. ArcGIS REST API specification defines feature set as a collection of features with a specific geometry type, fields, and a spatial reference. The JSON to Features tool can be used to convert Esri JSON directly into a feature class.

which leads to here

JSON To Features—Help | ArcGIS for Desktop

Re: How do I flip X/Y geometry in a feature class?

EricEagle — Tue, 18 Oct 2016 17:18:30 GMT

Joshua, yes, that's correct. It looks like this:

with arcpy.da.InsertCursor(pointFC, ['SHAPE@XY'] + fields) as prows:

for feature in geojson['features']:

geom = arcpy.AsShape(feature['geometry'], False)

if geom.type == 'point':

prows.insertRow([geom] + feature['properties'] for f in fields])

using the SHAPE@ token for line/poly types after that, etc..

Re: How do I flip X/Y geometry in a feature class?

TedKowal — Sat, 11 Dec 2021 15:52:19 GMT

I have not dealt with that specific problem, but I am working with SQL server with features converted to text strings (WKT) and mapping them over Bing Maps. SQL server stores the X,Y coordinate opposite of the way the Bing Maps API needs them, and a few other parens "()" formatting issues.... so I created a class in vb.net to rewrite the WKT stored in SQL Server flipping the XY coordinates on the fly.... Hopefully this will give you some ideas?

Imports Microsoft.VisualBasic

Namespace TSK.GML2VE
     Public Class GML2VE
          Private mGML As String = ""
          Private mFeatureType As String = ""
          Private mShapeID As String = ""
          Private mFID As Integer = 0
          Public Property ShapeID() As String
               Get
                    Return mShapeID
               End Get
               Set(ShapeID As String)
                    mShapeID = ShapeID
               End Set
          End Property

          Public Property FID() As Integer
               Get
                    Return mFID
               End Get
               Set(FID As Integer)
                    mFID = FID
               End Set
          End Property
          Public Property GML() As String
               Get
                    Return mGML
               End Get
               Set(GML As String)
                    mGML = GML
               End Set
          End Property
          Public Property FeatureType() As String 
               Get
                    Return mFeatureType
               End Get
               Set(FeatureType As String)
                    mFeatureType = FeatureType
               End Set
          End Property
          Public Function VE() As String
               If mGML = "" Or mFeatureType = "" Or mShapeID = "" Then
                    Return "Set GML, Feature Type"
               Else
                    Dim WKT As String = ""
                    Dim Output As String = ""
                    Dim VEGM As String = ""
                    Select Case mFeatureType
                         Case "Point"
                              'Get the WKT representation of the object
                              WKT = mGML
                              'Replace the double brakets that surround the coordinate pair
                              WKT = Replace(WKT, "POINT (", "")
                              ''Remove the closing double brackets 
                              WKT = Replace(WKT, ")", "")
                              'Build the Pushpin/GMarker object from the coordinates
                              VEGM = ""
                              Dim Coords() = Split(Trim(WKT), " ")
                              VEGM = VEGM + "new VELatLong(" + Coords(1) + "," + Coords(0) + ")"
                              Output += "var " + mShapeID + "=new VEShape(VEShapeType.Pushpin, " + VEGM + ");"
                         Case "LineString"
                              'Get the WKT
                              WKT = mGML
                              'Remove the Line String definition and opening bracket
                              WKT = Replace(WKT, "LINESTRING (", "")
                              'Remove the last bracket
                              WKT = Replace(WKT, ")", "")
                              'Create an Array of each point in the LineString
                              Dim PointArray() As String = Split(WKT, ",")
                              'Loop  through each point in the array
                              Dim i As Integer = 0
                              While i <= PointArray.Length - 1
                                   'Split the pint into individual coordinates
                                   Dim Coords() = Split(Trim(PointArray(i)), " ")
                                   'Build an array of the equivalent point definitions
                                   VEGM = VEGM + " new VELatLong(" + Coords(1) + "," + Coords(0) + "),"
                                   'Go on to the next point
                                   i = i + 1
                              End While
                              'Remove the trailing comma
                              VEGM = Left(VEGM, VEGM.Length - 1)
                              Output += "var " + mShapeID + "= new VEShape(VEShapeType.Polyline, [" + VEGM + "]);"
                              'Do Text and pretty stuff
                         Case "Polygon"
                              'Get the WKT representation of the object
                              WKT = mGML
                              'Replace the double brackets that surround the coordinate point pairs
                              WKT = Replace(WKT, "POLYGON ((", "")
                              'Remove the closing double brackets
                              WKT = Replace(WKT, "))", "")
                              'Create an array of each point in the Polygon 
                              Dim PointArray() As String = Split(WKT, ",")
                              'Build the appropriate VE/GMaps Polygon object from the coordinates
                              VEGM = ""
                              Dim i As Integer = 0
                              While i <= PointArray.Length - 1
                                   Dim Coords() = Split(Trim(PointArray(i)), " ")
                                   Coords(0) = Coords(0).Replace("(", "")
                                   Coords(1) = Coords(1).Replace(")", "")
                                   VEGM = VEGM + "new VELatLong(" + Coords(1) + "," + Coords(0) + "),"
                                   i = i + 1
                              End While
                              'Remove the last trailing comma
                              VEGM = Left(VEGM, VEGM.Length - 1)
                              'Add the constructor for the Polygon, and apply styling options
                              Output += "var " + mShapeID + "=new VEShape(VEShapeType.Polygon, [" + VEGM + "]);"
                    End Select
                    Return Output
               End If
          End Function
     End Class
End Namespace

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Re: How do I flip X/Y geometry in a feature class?

NeilAyres — Thu, 20 Oct 2016 11:36:47 GMT

list.reverse() method will swop each xy around.

Re: How do I flip X/Y geometry in a feature class?

DanPatterson_Retired — Sat, 11 Dec 2021 15:52:21 GMT

>>> a = np.arange(2*5).reshape(2,5).T
>>> a
array([[0, 5],
       [1, 6],
       [2, 7],
       [3, 8],
       [4, 9]])
>>> np.flipud(a)
array([[4, 9],
       [3, 8],
       [2, 7],
       [1, 6],
       [0, 5]])
>>> np.fliplr(a)
array([[5, 0],
       [6, 1],
       [7, 2],
       [8, 3],
       [9, 4]])‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

easier as well

Re: How do I flip X/Y geometry in a feature class?

NeilAyres — Sat, 11 Dec 2021 15:52:24 GMT

Somehow, I find this is easier to get my head around...

>>> 
>>> List = [[1,2],[3,4], [5,6], [6,7]]
>>> for l in List:
... l.reverse()
... 
>>> List
[[2, 1], [4, 3], [6, 5], [7, 6]]
>>>‍‍‍‍‍‍‍‍

Re: How do I flip X/Y geometry in a feature class?

DanPatterson_Retired — Sat, 11 Dec 2021 15:52:28 GMT

np.flipud(np.fliplr(a))
array([[9, 4],
       [8, 3],
       [7, 2],
       [6, 1],
       [5, 0]])‍‍‍‍‍‍‍‍‍‍‍‍

One more for the head .... just roll with it

>>> np.roll(a, 2, axis=0)
array([[3, 8],
       [4, 9],
       [0, 5],
       [1, 6],
       [2, 7]])‍‍‍‍‍‍

Re: How do I flip X/Y geometry in a feature class?

JoshuaBixby — Sat, 11 Dec 2021 15:52:31 GMT

Not incorporating the cursor part, the following will go through the features and swap all the coordinate pairs for points, lines, etc.... and create geometries:

for feature in geojson['features']:
    geom_geojson = feature['geometry']
    coords = geom_geojson['coordinates']
    if geom_geojson['type'] == "Point":
        geom_geojson['coordinates'] = coords[::-1]
    else:
        geom_geojson['coordinates'] = [coord[::-1] for coord in coords]
    geom = arcpy.AsShape(geom_geojson, False)‍‍‍‍‍‍‍‍