Rendering choropleth without fill

[vgoklani]

Hello - I would like to render two types of data on the same map: The datasets are:

1. a polygon (connected line segments) from a geojson file. I was able to render this as a ChoroplethViz, but I had to create a fake "density" value to get the Viz to render. I only need to render the lines on the map (to define boundaries). Is that possible? Here's my ChoroplethViz approach:

   viz = ChoroplethViz("precincts.geojson",
   access_token=token,
   color_property='density',
   color_stops=create_color_stops([0, 50, 100, 500, 1500], colors='YlOrRd'),
   color_function_type='interpolate',
   line_stroke='--',
   line_color='rgb(128,0,38)',
   line_width=1,
   opacity=0.8,
   center=(-82.9988, 39.9612),
   zoom=9.5,
   legend_layout='horizontal',
   legend_key_shape='bar',
   legend_key_borders_on=False,
   style='mapbox://styles/mapbox/dark-v9?optimize=true',
   below_layer='waterway-label',
   height='900px',
   )
   viz.show()

The lines don't get rendered if I remove the color_property.

2. I would like to draw circles on top of the lines, (with different colors/radii). How do I add a second layer for this dataset? I saw a few open tickets regarding adding a second layer, but I don't see any updates in the examples directory. Is this currently in the master branch? Thanks

[akacarlyann]

@vgoklani You're right, multi-layer support is still pending. I started working on this last week, so stay tuned!

I'm adding a PR (#157) to separate opacity from line opacity in the ChoroplethViz. You can try it out here:

viz = ChoroplethViz('precincts.geojson', 
                    access_token=token,
                    color_stops=[],
                    line_stroke='-',
                    line_color='white',
                    line_width=1,
                    opacity=0,
                    line_opacity=1,
                    center=(-82.9988, 39.9612),
                    zoom=9.5,
                    style='mapbox://styles/mapbox/dark-v9?optimize=true',
                    height='900px')
viz.show()

No need to set a color_property. For now, set color_stops to [] if you don't want to define a list of key-color pairs.

[akacarlyann]

Also, @vgoklani , since we already have a ticket for rendering multiple layers, are you okay if I edit the name of this issue to match the question you had about the choropleth fill?

[vgoklani]

of course - thanks again for your help!

[akacarlyann]

No problem -- hollow polygons is a good use case to know about!