Add support to show polygons

Hi there,

I would like to add support to show polygons. Before I start with an implementation, I would like to discuss with you the best approach.

I was thinking about the following steps:

1. Create a new template polygon.html.
2. Create in viz.py a new Class PolygonViz.
3. Create in viz.py a new base Class Viz. PolygonViz, GraduatedCircleViz, and CircleViz inherit from this Class. Below is the rough outline of the Viz Class.
4. Create one polygon example jupyter notebook that proves the implementation.

I am happy for any feedback about the above. Since I am new to the project, I am also open for a complete different approach to show polygons.

Looking forward to work on this 😊

---

class Viz(object):
    """Base class for all visualisations"""

    def __init__(self,
                 access_token=None,
                 center=(0, 0),
                 div_id='map',
                 height='500px',
                 style_url="mapbox://styles/mapbox/light-v9?optimize=true",
                 width='100%',
                 zoom=0):

        if access_token is None:
            access_token = os.environ.get('MAPBOX_ACCESS_TOKEN', '')
        if not access_token.startswith('pk'):
            raise TokenError('Mapbox access token must be public (pk)')
        self.access_token = access_token

        self.div_id = div_id
        self.width = width
        self.height = height
        self.data = data
        self.style_url = style_url
        self.center = center
        self.zoom = zoom

    def as_iframe(self, html_data):
        """Build the HTML representation for the mapviz."""
        ...
       
    def show(self, **kwargs):
        """Load the HTML iframe and display the  the iframe in the current jupyter notebook view"""
        ...

[ustroetz]

Glad to see that someone picked up the work! Sorry that I was a bit slow on this. Awesome to see that there is now so much traction on the project 👏

[ustroetz]

Yes, I actually have a branch sitting here that I want to finish up 😃

I’ll try to open a PR by the end of the week 🤞