topic Re: Working from geometry to feature to map, can't display polygon feature in ArcGIS API for Python Questions

Working from geometry to feature to map, can't display polygon feature

JillKelly — Thu, 26 Jan 2017 16:37:14 GMT

I've created a valid polygon geometry.

CTcorners = { 'rings' : [[[-72.0,42.0],[-72.1,42.0],[-72.1,42.1],[-72.0,42.1],[-72.0,42.0]]]} # clockwise
CTpolygeom = arcgis.geometry.Polygon(CTcorners)

I converted it to a feature.

CTpoly = arcgis.features.Feature(CTpolygeom)

That step seems to work properly, but when I try to add it to the map,

map2 = gis.map('Connecticut') # focus on CT
map2.basemap = 'topo'
map2.add_layer(CTpoly)
map2

it throws the error:

TypeError: argument of type 'Feature' is not iterable

on the add_layer line. Do I need to make a layer of it for display maybe?

ps -- is 'rings' a reserved term in this context or arbitrary? Thanks.

Re: Working from geometry to feature to map, can't display polygon feature

XuehanJing — Thu, 26 Jan 2017 18:01:01 GMT

Hi Jill,

From the API documentation, I can tell the add_layer is used to add an existing item from your portal.

arcgis.widgets module — arcgis 1.0 documentation

Since your CTPloy is not an item, it may not work.

Maybe you can try draw(), arcgis.widgets module — arcgis 1.0 documentation

Thanks.

Re: Working from geometry to feature to map, can't display polygon feature

JillKelly — Thu, 26 Jan 2017 20:03:14 GMT

"item" seems a little vague. I can, for example, add_layer a set of points:

df1 = pandas.read_csv('CTpolygon.csv', header=0, names=['longitude', 'latitude'])
rows = np.random.choice(df1.index.values, 499)
df = df1.ix[rows]
CTpoints = gis.content.import_data(df)
map1 = gis.map('Connecticut') # focus on CT
map1.basemap = 'topo'
map1.add_layer(CTpoints)
map1

How is a polygon feature any different in terms of being an "item"?

Re: Working from geometry to feature to map, can't display polygon feature

RohitSingh2 — Mon, 06 Feb 2017 19:32:12 GMT

A Feature is not a layer and you wont be able to use map.add_layer() to draw the feature in the map widget. You can convert the feature to a featureset and use map.draw() to draw it:

map.draw(FeatureSet([CTpoly]))

import_data() results in a FeatureCollection which is a layer that can be added to a map widget.

Re: Working from geometry to feature to map, can't display polygon feature

JillKelly — Tue, 07 Feb 2017 14:38:47 GMT

Thanks Rohit. I had tried converting it to a Layer, but I overlooked FeatureSet. It works!