topic Re: Convert lat-long to WKT spatial reference? in Python Questions

Convert lat-long to WKT spatial reference?

RickThiel — Mon, 15 Feb 2016 22:34:35 GMT

Hello, arcpy newbie here... sorry if I am asking a basic question. I am looking for help on transforming lat/long decimal degrees to a different spatial reference, specifically a well-known-text (WKT) custom reference that we are using.

I have sent a street address to an address locator (findAddressCandidates) and it returns JSON back to me. If the candidate score is near 100, then I parse the JSON to grab the lat/long. That all works fine. But, now I would like to use an insertCursor to add this point to my feature class. I am unclear how I would convert a lat long to the custom spatial ref., WKT?

I have been trying many different things in the past few days but nothing works for me. I have tried passing the WKT in the URL for the address locator. It seems like the locator does not recognize the WKT and converts it to the default 4326 spatial reference (not what I want).

FYI.. this is the custom spatial reference that I am using:

PROJCS["NAD_1983_Lambert_Conformal_Conic",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Conformal_Conic"],PARAMETER["False_Easting",1840330.965],PARAMETER["False_Northing",527997.6316666666],PARAMETER["Central_Meridian",-92.0],PARAMETER["Standard_Parallel_1",41.15],PARAMETER["Standard_Parallel_2",45.0],PARAMETER["Latitude_Of_Origin",40.15],UNIT["Foot_US",0.3048006096012192]]

Thanks, --Rick

Re: Convert lat-long to WKT spatial reference?

DanPatterson_Retired — Tue, 16 Feb 2016 00:00:14 GMT

you still have to project from your initial coordinate system to your desired on...

Project—Help | ArcGIS for Desktop

see the code snippet

However in the geometry classes, WKT etc are read-only properties

Geometry—Help | ArcGIS for Desktop

but once projected, you can get it back out to JSON

but a simpler solution would be just to use the PointGeometry class and snag the point coordinates after they are projected if all you need to know is the values

Re: Convert lat-long to WKT spatial reference?

RickThiel — Wed, 17 Feb 2016 22:24:46 GMT

Thanks Dan for pointing me in the right direction. The example on the ESRI help page shows that when they Project a point, they immediately save it to an output feature class. Is there any way to project the point feature on the fly without having to save it to an output file/db?

For example, the geo-coder returns a point with coordinates x=-90.079346, y=42.718911 (spatial ref = 4326). Could I take those coordinates and project them on the fly to return the true coordinates that I want?

Re: Convert lat-long to WKT spatial reference?

DanPatterson_Retired — Wed, 17 Feb 2016 22:39:11 GMT

of course

in the PointGeometry class

PointGeometry—Help | ArcGIS for Desktop

a PointGeometry object needs a point (long story), so you are there.

projectAs (spatial_reference, {transformation_name})

Projects a geometry and optionally applies a geotransformation.

To project, the geometry needs to have a spatial reference, and not have an UnknownCoordinateSystem. The new spatial reference system passed to the method defines the output coordinate system. If either spatial reference is unknown the coordinates will not be changed. The Z- and measure values are not changed by the ProjectAs method.

Re: Convert lat-long to WKT spatial reference?

RickThiel — Wed, 17 Feb 2016 22:48:38 GMT

OK, I think I understand. But, because I am using a custom projection, won't that be a problem? In the projectAs() method, it says "To project, the geometry needs to have a spatial reference, and not have an UnknownCoordinateSystem"

Re: Convert lat-long to WKT spatial reference?

DanPatterson_Retired — Wed, 17 Feb 2016 22:52:40 GMT

but you do have a spatial reference in your example from the geocoder... 4326 by the coordinates. That I presume is what they are coming in as...define it as such, then set the output projection

Re: Convert lat-long to WKT spatial reference?

RebeccaStrauch__GISP — Sat, 11 Dec 2021 22:17:19 GMT

Since I've been working on something similar the past couple days (not the json part), I'll throw this out there. I'm not sure how you parsed your lat, longs, but this assuming a PtID, long, lat like

ptList = [[104, -148.631196, 64.010037], [102, -147.707779, 63.680584], [103, -147.469019, 63.975227]]

This script will take a structure like that, create a FC in DD, add the x/y as fields for kicks, then project to you desired wkid (mine is 3338, AK Albers). I have also used AlterField (not shown here) on the field POINT_X, POINT_Y so I could use the addxy again in the projected FC (and a bunch of other fields). If you don't have a PtID field,m or you input is a bit different, that will have to be modified.

See if this will help.

import os
import arcpy
from arcpy import env

theWorkspace = r'C:\__temp\test.gdb'
arcpy.env.workspace = theWorkspace   #not until final save
arcpy.env.overwriteOutput = True    

# pts with a ID, long, lat
ptList = [[104, -148.631196, 64.010037], [102, -147.707779, 63.680584], [103, -147.469019, 63.975227]]

ptFields = [["PtID", "SHORT", "5", "", ""]]
newFcs = [["newpts", ptFields]]    # , ["tmppt2", pt2Fields], ["tmppt3", pt2Fields]]
newFCMySR = "newPtsMySR"

mySR = arcpy.SpatialReference(3338)
geoSR = arcpy.SpatialReference(4269)

for newFC, fields in newFcs:
  print(newFC)
  if not arcpy.Exists(arcpy.os.path.join(theWorkspace, newFC)):
    print("{0} does not exists, creating....".format(newFC))
    arcpy.CreateFeatureclass_management(theWorkspace, newFC, "POINT", "", "", "", initialSR) 
    for addFld in fields:
      arcpy.AddField_management(newFC, addFld[0], addFld[1], addFld[2], addFld[3], addFld[4])
      print(" ..added field {0} to {1}".format(addFld[0], newFC))
    #listNewFields = arcpy.ListFields(newFC)
  else:
    print("{0} exists".format(newFC))

for newFC, newFields in newFcs:
  fldNames = []
  iCurFields = ['SHAPE@XY']
  for fn in newFields:
    print(fn[0])
    fldNames.append(fn[0])
    iCurFields.append(fn[0])
  print("\nField names in lists {0}: {1}".format(newFC,fldNames))
  print("   and for the cursor: {0}".format(iCurFields))
  cursor = arcpy.da.InsertCursor(newFC, iCurFields)
  print(" ->working with {0}".format(newFC))

  for ptID, x, y in ptList:
    print(ptID)
    xy = (x, y)
    print(xy)
    cursor.insertRow([xy, ptID])
  
  arcpy.AddXY_management(newFC)

arcpy.Project_management(newFC, newFCMySR, mySR)

Re: Convert lat-long to WKT spatial reference?

RandyBurton — Sat, 11 Dec 2021 22:17:22 GMT

Does something like this help:

import arcpy
# WGS 1984 : (4326) Lat/Lon
x = -89.384171
y = 43.074743
# xy = Wisconsin Capitol

sr = arcpy.SpatialReference(r'C:\path2file\custom.prj') # your projection file

ptGeometry = arcpy.PointGeometry(arcpy.Point(x,y),arcpy.SpatialReference(4326)).projectAs(sr)

print ptGeometry.JSON
print x, y
print ptGeometry.firstPoint.X, ptGeometry.firstPoint.Y
# converted xy = 2538768.50758 1604492.87376

Re: Convert lat-long to WKT spatial reference?

RebeccaStrauch__GISP — Fri, 19 Feb 2016 00:23:06 GMT

Randy, thanks for that. I think I'll go back to my process and see if I can use that instead of the projection process I've been doing. Only reason I was doing that was to get the coords. You way is nice and clean.

Re: Convert lat-long to WKT spatial reference?

RandyBurton — Sat, 11 Dec 2021 22:17:24 GMT

If you know the reference numbers, you can use this instead:

# WGS 1984 : (4326) Lat/Lon
# WGS 1984 Web Mercator (auxiliary sphere) : (102100) or (3857)
ptGeometry = arcpy.PointGeometry(arcpy.Point(x,y),arcpy.SpatialReference(4326)).projectAs(arcpy.SpatialReference(3857))

Re: Convert lat-long to WKT spatial reference?

DanPatterson_Retired — Fri, 19 Feb 2016 01:34:20 GMT

Rick ...

if you want to weigh in here anytime... the suggestions are piling up... I will whip in a numpy solution if this isn't closed soon

Re: Convert lat-long to WKT spatial reference?

RebeccaStrauch__GISP — Fri, 19 Feb 2016 02:05:55 GMT

Randy's solution was great for me (I do use the SR #'s) except since they were just one points I used .centroid instead of .startpoint. this saved two projections/addXY/AlterField on 3 different files for me. This is why I really like geonet.

If anyone has a simple solution using the geometry for converting the long, lat values to DDM and DMS (into new fields) other than using the Convert Coordinate Notation—Help | ArcGIS for Desktop which works great and adds the new fields, but to a new FC each time (3 times x 3 files in my case), I would love to see it. I may just do the conversion/formatting in a and add the values to my [ ].

Dan....simple Numpy suggestion perhaps? DD (negative long in my case) -> DDM and DMS? I can fire this off to a new question if needed, but I know there are already thread on the conversion (and I have snippets already)

Re: Convert lat-long to WKT spatial reference?

RandyBurton — Sat, 11 Dec 2021 22:17:27 GMT

Getting off topic a little... Rebecca, you could write a function. For DD to DMS, something like:

def dd2dms(dd,xy):
    is_positive = dd >= 0
    dd = abs(dd)
    m,s = divmod(dd*3600,60)
    d,m = divmod(m,60)
    if is_positive:
        if xy == 'lat' : nsew = ' N'
        else : nsew = ' E'
    else:
        if xy == 'lat' : nsew = ' S'
        else : nsew = ' W'
    return str(int(d))+' '+str(int(m))+' '+str(round(s,1))+ nsew

print 61.217176, -149.889006
print dd2dms(61.217176,'lat'), dd2dms(-149.889006,'lon')
# 61 13 1.8 N 149 53 20.4 W

Re: Convert lat-long to WKT spatial reference?

DanPatterson_Retired — Fri, 19 Feb 2016 07:03:20 GMT

Rebecca, you probably haven't had time to scroll around the Numpy Repository, but I have this in there

Converting Decimal Degrees to DMS format (there is a zip as well)

Re: Convert lat-long to WKT spatial reference?

RickThiel — Fri, 19 Feb 2016 14:22:30 GMT

Thanks Rebecca,

I started going down the same route you chose, by creating a temp GDB to store the new projected coordinates. Late yesterday, I finally got a good result! Yeah! I was going to reply to your suggestion, but I was too tired last night and I went home instead.

Now, I see the suggestion from your fellow Alaskan, Randy Burton this morning and it seems like a much cleaner way to go. I think that is what I will use. Time to rip out some code...

Thanks Dan Patterson Rebecca Strauch, GISP and Randy Burton for all of your help and attention.

Take care, --Rick

Re: Convert lat-long to WKT spatial reference?

RickThiel — Fri, 19 Feb 2016 14:25:59 GMT

Thanks Randy! That's exactly what I was looking for!

Nice touch using the Wisconsin Capitol. Rebecca's lat/long examples were SO confusing to me! Haha. I mean, -147.707779, 63.680584, what is that??? Sara Palin's house?

Take care everybody! Thanks again! -_Rick

Re: Convert lat-long to WKT spatial reference?

RebeccaStrauch__GISP — Mon, 22 Feb 2016 19:31:40 GMT

Thanks Dan/Randy. I'll check out the code snippets, I'm sure one (or both) will work for me.

Re: Convert lat-long to WKT spatial reference?

JohnMcoy — Tue, 02 May 2017 08:34:21 GMT

hi Randy, how can I take x,y coordinates from featureclass? Because I don`t have xy values in code.

Re: Convert lat-long to WKT spatial reference?

RandyBurton — Sat, 11 Dec 2021 22:17:29 GMT

Using a search cursor, you can loop through the points in a feature class, read the geometry and convert to longitude/latitude. Something like this:

for row in arcpy.da.SearchCursor("MyPointLayer",["OID@","SHAPE@XY"]):

     print("Feature {}:".format(row[0])),

     px, py = row[1]
     print("{}, {}".format(px, py)),

     # WGS 1984 : (4326) Lat/Lon  
     # WGS 1984 Web Mercator (auxiliary sphere) : (102100) or (3857)  
     ptGeometry = arcpy.PointGeometry(arcpy.Point(px,py),arcpy.SpatialReference(3857)).projectAs(arcpy.SpatialReference(4326))

     print ptGeometry.firstPoint.X, ptGeometry.firstPoint.Y‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

This code may be helpful in getting the spatial reference information for the point feature:

SR = arcpy.Describe("MyPointLayer").spatialReference
print SR.name
print SR.factoryCode‍‍‍‍‍‍

Re: Convert lat-long to WKT spatial reference?

JohnMcoy — Wed, 03 May 2017 06:31:01 GMT

Could you explain, how to separate coordinates in different columns ? Now I have coordinates like this(photo). I want 4 different columns Point X Point Y in WGS1984 and POINT X POINT Y in WGS 1984 Web Mercator..