topic Re: fail to build polygon geometry from Lat/Long in Python Questions

fail to build polygon geometry from Lat/Long

KevinBell — Sat, 11 Dec 2021 20:29:44 GMT

import arcpy
array = arcpy.Array([arcpy.Point(0, 0),
                     arcpy.Point(0, 1000),
                     arcpy.Point(1000, 1000),
                     arcpy.Point(1000, 0)
                     ])
polygon = arcpy.Polygon(array)
cursor = arcpy.da.InsertCursor(r'C:\path\to\your\geodatabase.gdb\polygon', ['SHAPE@'])
cursor.insertRow([polygon])

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The code below works as expected, but fails if I substitute Lat/Longs in the arcpy.Point.  Is that expected?

Re: fail to build polygon geometry from Lat/Long

DanPatterson_Retired — Fri, 23 Sep 2016 20:06:46 GMT

Kevin can you format your code using syntax highlighting /blogs/dan_patterson/2016/08/14/script-formatting

EDIT What are the longitudes and latitude? some example? longitude first (X), latitude 2nd (Y)

Re: fail to build polygon geometry from Lat/Long

DarrenWiens2 — Fri, 23 Sep 2016 20:11:47 GMT

Can you provide an example where it fails? Or does your given example fail?

Re: fail to build polygon geometry from Lat/Long

KevinBell — Sat, 11 Dec 2021 20:29:47 GMT

this doesn't work:

array = arcpy.Array([arcpy.Point(-111.8256, 40.691085),
                     arcpy.Point(-111.825347, 40.691614),
                     arcpy.Point(-111.824706, 40.691896),
                     arcpy.Point(-111.825592, 40.68703)
                     ])‍‍‍‍‍

Re: fail to build polygon geometry from Lat/Long

KevinBell — Fri, 23 Sep 2016 20:13:41 GMT

when I pass in the -111.8256, 40.691085 as above a record is created in the table, but w/ empty geometry.

Re: fail to build polygon geometry from Lat/Long

DanPatterson_Retired — Fri, 23 Sep 2016 20:14:07 GMT

is the polygon ring (aka points) clockwise in orientation? and non-intersecting? (i'm not going to draw it out... the numbers just got weird)

Re: fail to build polygon geometry from Lat/Long

DarrenWiens2 — Fri, 23 Sep 2016 20:14:47 GMT

How does it fail? With an error? If so, what's the full error?

I suspect it's because you don't set a spatial reference anywhere, but we'll see.

Re: fail to build polygon geometry from Lat/Long

DarrenWiens2 — Fri, 23 Sep 2016 20:18:43 GMT

What is the spatial reference of your 'polygon' feature class?

Re: fail to build polygon geometry from Lat/Long

KevinBell — Fri, 23 Sep 2016 20:22:39 GMT

GCS_WGS_1984 is the spref of the FC I'm inserting into.

Re: fail to build polygon geometry from Lat/Long

KevinBell — Fri, 23 Sep 2016 20:23:45 GMT

I drew it out and it looks like it's clockwise, non-intersecting.

Re: fail to build polygon geometry from Lat/Long

DarrenWiens2 — Sat, 11 Dec 2021 20:29:50 GMT

Can you try this?


import arcpy
fc = r'C:\path\to\your\geodatabase.gdb\polygon'
sr = arcpy.Describe(fc).spatialReference # get spatial reference
array = arcpy.Array([arcpy.Point(-111.8256, 40.691085),
                     arcpy.Point(-111.825347, 40.691614),
                     arcpy.Point(-111.824706, 40.691896),
                     arcpy.Point(-111.825592, 40.68703)
                     ])
polygon = arcpy.Polygon(array,sr) # create polygon with spatial reference
cursor = arcpy.da.InsertCursor(fc, ['SHAPE@'] )
cursor.insertRow([polygon])‍‍‍‍‍‍‍‍‍‍‍

Re: fail to build polygon geometry from Lat/Long

KevinBell — Fri, 23 Sep 2016 20:31:03 GMT

Much thanks! I thought it'd pick up the sr on it's own!