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Reprojecting tabular data without creating feature class?

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01-29-2019 03:44 PM
Arne_Gelfert
Frequent Contributor

Okay, I realize I may draw the scorn from the community for asking the way I'm asking but ...Is there an easy way (easier than what I'm doing) to read Lat/Lon values stored in a non-spatial SQL table, reproject them and write the new values back to same or other table? Since this is for a non-GIS audience, I don't have any use for creating an intermediate feature class. I found arcpy.AddXY_management. But I believe, as most other scenarios I could come up with, requires a feature class. Basically, I'm curious if there is another way to do this without creating a feature class.

This is what I tried:

import pyodbc

sql_conn = pyodbc.connect('''bla bla bla''') 
query = '''SELECT [LATITUDE],[LONGITUDE]
           FROM MyTable'''

cursor = sql_conn.cursor()
cursor.execute(query)

ptDataRows = []

for row in cursor.fetchall():
    #Turn cursor row into list
    ptDataRows.append([x for x in row])

I was bringing in additional attributes from my source table which I'm leaving out in this example. But a longer list would be the only difference. Next I'm working with the Lat/Lon columns to create point geometries and then 

import arcpy

src_sr = arcpy.SpatialReference(4267) 
dest_sr = arcpy.SpatialReference(4326)

for i,row in enumerate(ptDataRows):

    pt = arcpy.Point(row[0],row[1])
    ptGeom = arcpy.PointGeometry(pt, src_sr)
 
    newpoint = ptGeom.projectAs(dest_sr,'NAD_1927_To_WGS_1984_4')
    newcoord = [round(newpoint.centroid.X,7),round(newpoint.centroid.Y,7)]
 
    pt_attrs = row.extend(newcoord)

Now, I have a new list of lists, each containing the data for a new table row that I can write back to a target table. -- I also looked at arcpy.project_management. But besides the hilarious name that will make any PMP laugh, I couldn't get it to work. I think it requires a feature class again.

Since this works as it, I have to mention that I'm needing to append additional spatial attributes such as UTM zones. That's why I'm wondering if this is the "best" approach.

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10 Replies
BruceHarold
Esri Regular Contributor

I tried a workflow starting with a non-spatial table in SQL Server using Convert Coordinate Notation with no change in actual notation but a change in projection, then run Add XY Coordinates but its long winded.  The right people here at Esri have been informed.

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