Is my topojson file structured properly in order to render a map on folium? - topojson

Question

I've downloaded the us-counties shapefile from the US census bureau and converted it into topojson file using mapshaper.com. Unfortunately, I have to parse through the topojson quite a bit to get the FIPS county code. I'm using Folium to render the map but keep getting an error.
I've taken my dataframe and made it into a series of FIPS_codes and $amounts. Using the style_function, I call the FIPS_codes from the topojson file and compare that value to the series to render a map of us-counties.
import branca
colorscale = branca.colormap.linear.YlOrRd_09.scale(0, 50e3)
def style_function(feature):
county_dict = cms_2017_grouped_series.get(
features['objects']['tl_2017_us_county']['geometries']['properties']['GEOID'], None)
return {
'fillOpacity': 0.5,
'weight': 0,
'fillColor': '#black' if employed is None else colorscale(employed)
}
The error I'm getting is AttributeError: 'list' object has no attribute 'get'
The rest of code needed to render the map is below
m = folium.Map(
location=[48, -102],
tiles='cartodbpositron',
zoom_start=3
)
folium.TopoJson(
json.load(open(county_geo)),
'objects.tl_2017_us_county.geometries.properties.GEOID',
style_function=style_function
).add_to(m)

Answer 1

I followed your steps to create the topojson and good news, it checks out. Just need to change up a couple of things with your code
I created some mock user data first. I'm using geopandas and the topjson file to make it easy on myself, but you would just use your pandas dataframe that contains county and employment numbers
import geopandas as gpd
gdf = gpd.read_file('tl_2017_us_county.json')
gdf['employed'] = np.random.randint(low=1, high=100000, size= len(gdf))
Create a Series using your dataframe. This will be used in the style func to "bind" your data to the map
cms_2017_grouped_series = gdf.set_index('GEOID')['employed']
print(cms_2017_grouped_series.head())
GEOID
31039 54221
53069 68374
35011 8477
31109 2278
31129 40247
Name: employed, dtype: int64
This is pretty close to your style function. I've just changed the line with the .get() to use the corrected dict keys of feature. Oh and I'm using the return value(employed) in the fillColor below
import branca
colorscale = branca.colormap.linear.YlOrRd_09.scale(0, 50e3)
def style_function(feature):
employed = cms_2017_grouped_series.get(feature['properties']['GEOID'], None)
return {
'fillOpacity': 0.5,
'weight': 0,
'fillColor': '#black' if employed is None else colorscale(employed)
}
Slight mod of the object_path is next. I'm also saving the map and then opening it in Chrome since it wouldn't render in my notebook due to the size
m = folium.Map(
location=[48, -102],
tiles='cartodbpositron',
zoom_start=3
)
folium.TopoJson(open('tl_2017_us_county.json'), 'objects.tl_2017_us_county',
style_function=style_function).add_to(m)
m.save('map.html')