How do I convert existing fields to lat and long using the Calculate Field tool?

Question

I am trying to convert my X and Y fields from feet to lat and long. I can easily do this in Calculate Geometry from the attribute table, but I'm needing to use this in a model and Calculate Geometry is not available as a tool. I'm using the Calculate Field tool and trying to find a script that converts this to lat and long. I've tried the following script using the advanced code for VBA with no luck:

Dim dblX As Double
Dim pPoint As IPoint
Set pPoint = [Shape]
dblX = pPoint.X

dblX

I'd like to avoid having to create a totally new shapefile or feature class. I just want to change the existing fields in this existing feature class.

Thanks!!

Answer 1

Here are some Calculate Field examples. If you scroll down about 3/4 of the way you'll see some examples for Geometry Unit conversion.

For scripting, you might consider adding fields as opposed to editing existing ones.

Answer 2

How about Calculate Field or Add XY Coordinates? I think in the latter, the data will already have to be in a geographic coordinate system (but it looks like it is).

Answer 3

Sorry for the late response but I just happened on this forum looking for help on another topic. I too needed a way to add Lat/Long fields to my records for reference from other non-spatial applications. I wrote an ArcPy script which adds and calculates Lat/Long fields for all visible feature layers in your map (so if you don't want fields added to a layer then turn it off!) You would need to make 2 revisions to this code in order to make it work for you: 1) This script creates a temporary layer, WGS_Output, which is created in WGS_1984 coordsys. You need to modify line 5 to point at your default workspace. 2) Line 12 performs a join between the original layer and the WGS_Output layer. I used the OBJNAME field which is a required/unique field generated by the Topcon Survey Controller we use. If you don't have a unique field like this you will need to add one to successfully perform the join.

import arcpy
import getpass

user = getpass.getuser()
mxd = arcpy.mapping.MapDocument("CURRENT")
WGS_Output = "C:\\Users\\"+user+"\\My Documents\\ArcGIS\\Default.gdb\\WGS_Output"

for lyr in arcpy.mapping.ListLayers(mxd):
    if(lyr.visible & lyr.isFeatureLayer):
        arcpy.AddField_management(lyr.name, "LONGITUDE", "DOUBLE", "", "", "", "", "NON_NULLABLE", "NON_REQUIRED", "")
        arcpy.AddField_management(lyr.name, "LATITUDE", "DOUBLE", "", "", "", "", "NON_NULLABLE", "NON_REQUIRED", "")
        arcpy.Project_management(lyr.name, WGS_Output, "GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]]", "NAD_1983_To_WGS_1984_5", "")
        arcpy.AddXY_management(WGS_Output)
        arcpy.AddJoin_management(lyr.name, "OBJNAME", WGS_Output, "OBJNAME", "KEEP_COMMON")
        arcpy.CalculateField_management(lyr.name, lyr.name+".LONGITUDE", "[WGS_Output.POINT_X]", "VB", "")
        arcpy.CalculateField_management(lyr.name, lyr.name+".LATITUDE", "[WGS_Output.POINT_Y]", "VB", "")
        arcpy.RemoveJoin_management(lyr.name, "WGS_Output")

Good Luck, Mike