JSON string input coordinate pairs

[JamesCrandall]

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

[BruceHarold · Accepted solution]

Try importing the json module and use json.loads

Regards

[JamesCrandall]

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

[JamesCrandall]

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)

[WesMiller]

I did one using the following code(async)

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

[JamesCrandall]

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!

[WesMiller]

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)

[BruceHarold]

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.

[JamesCrandall]

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"!