topic Re: JSON string input coordinate pairs in Python Questions

JSON string input coordinate pairs

JamesCrandall — Mon, 14 Sep 2015 17:27:59 GMT

I am unable to properly setup a Toolbox script with a single input parameter to parse a json string. I will be receiving the JSON as:

{

"rings" :
    [

[[-117,34],[-116,34],[-117,33],[-117,34]],

[[-115,44],[-114,43],[-115,43],[-115,44]]

]
},
{

"rings" :
    [

[[32,17],[31,17],[30,17],[30,16],[32,17]]

]
}

So far I have tried to setup the script/tool with a String parameter and attempted to pull in the coordinate pairs and create a polygon feature but it's treating the entire string as a single value and I'm not sure of the best way to parse it into float values.

Any input is appreciated

Re: JSON string input coordinate pairs

BruceHarold — Mon, 14 Sep 2015 17:46:05 GMT

Try importing the json module and use json.loads

Regards

Re: JSON string input coordinate pairs

JamesCrandall — Sat, 11 Dec 2021 22:09:48 GMT

Thanks Bruce!

I've updated the input json string to incorporate a geoJSON format so that it's easier to just convert to polygons. My task is to return a centroid xy for the input point features (which is why I am attempting to construct a polygon).

The below is failing on the arcpy.AsShape()

feature_info = '{"type": "polygon", "coordinates": [[-117.00,34.00],[-116.00,34.00],[-117.00,33.00],[-117.00,34.00]],"spatialReference" : {"wkid" : 4326}}'
jstr = json.loads(feature_info)
print jstr
inpoly = arcpy.AsShape(jstr) #fails with error: type object argument after * must be a sequence, not a float
pcent = arcpy.Point
pcent = inpoly.centroid
pcx = pcent.X
pcy = pcent.Y

Re: JSON string input coordinate pairs

WesMiller — Sat, 11 Dec 2021 22:09:51 GMT

I did one using the following code(async)

import urllib
import json
URL  = 'your/url'
result = urllib.urlopen(URL).read()
addrData = json.loads(result)

Re: JSON string input coordinate pairs

JamesCrandall — Sat, 11 Dec 2021 22:09:53 GMT

Oh! I see my error!

This has the correct JSON format:

feature_info = '{"type": "polygon", "coordinates": [[[-117.00,34.00],[-116.00,34.00],[-117.00,33.00],[-117.00,34.00]]]}'
jstr = json.loads(feature_info)
print jstr
inpoly = arcpy.AsShape(jstr) #fails with error: type object argument after * must be a sequence, not a float
pcent = arcpy.Point
pcent = inpoly.centroid
pcx = pcent.X
pcy = pcent.Y
print str(pcx) + " / " + str(pcy)

Re: JSON string input coordinate pairs

JamesCrandall — Mon, 14 Sep 2015 18:12:55 GMT

Thanks Wes!

I'm still not entirely certain how this will all be integrated. I've been asked to create a Geoprocessing Service and my original thought was the calling app would pass in a JSON string (as in my OP). So at the moment I'm just trying to figure out how to just hardcode this as a python script and then eventually publish it as a service.

Can you suggest the type of input parameter I should consider? Per your sample, it'd be a "String" representation of the url, correct?

Thanks!

Re: JSON string input coordinate pairs

WesMiller — Mon, 14 Sep 2015 18:26:33 GMT

Yes you are correct. It is a string representation, in my case i'm passing 'url?'+'Street=' + address + '&outFields=&maxLocations=&outSR='+str(src)+'&searchExtent=&f=Json' to a published geocoder and getting the x,y to determine if the user is in or out of ball districts(soccer, baseball)

Re: JSON string input coordinate pairs

BruceHarold — Mon, 14 Sep 2015 18:51:06 GMT

If this is all Esri stack then you can publish a feature service of your polygons that you're testing for intersection and use the geocode JSON as input to a Query call and check for distance.

Re: JSON string input coordinate pairs

JamesCrandall — Mon, 14 Sep 2015 19:39:04 GMT

Update:

I successfully published the service and able to execute the task, pass in a well-formatted JSON string and return the centroid coordinates. As the service publisher, I'm just going to place the requirements on the application developer to perform the necessary formatting.

note: oh how things have changed and now I'm the "configuration specialist" instead of the "app developer"!