Creating a polygon from a list of points¶

# Imports
import folium
import random
from scipy.spatial import ConvexHull

# Function to create a list of some random points
def randome_points(amount, LON_min, LON_max, LAT_min, LAT_max):

    points = []
    for _ in range(amount):
        points.append((random.uniform(LON_min, LON_max),random.uniform(LAT_min, LAT_max)))

    return(points)

# Function to draw points in the map
def draw_points(map_object, list_of_points, layer_name, line_color, fill_color, text):

    fg = folium.FeatureGroup(name=layer_name)

    for point in list_of_points:
        fg.add_child(folium.CircleMarker(point, radius=1, color=line_color, fill_color=fill_color,
                                         popup=(folium.Popup(text))))

    map_object.add_child(fg)

# Function that takes a map and a list of points (LON,LAT tupels) and
# returns a map with the convex hull polygon from the points as a new layer

def create_convexhull_polygon(map_object, list_of_points, layer_name, line_color, fill_color, weight, text): 

    # Since it is pointless to draw a convex hull polygon around less than 3 points check len of input
    if len(list_of_points) < 3:
        return

    # Create the convex hull using scipy.spatial 
    form = [list_of_points[i] for i in ConvexHull(list_of_points).vertices]

    # Create feature group, add the polygon and add the feature group to the map 
    fg = folium.FeatureGroup(name=layer_name)
    fg.add_child(folium.vector_layers.Polygon(locations=form, color=line_color, fill_color=fill_color,
                                              weight=weight, popup=(folium.Popup(text))))
    map_object.add_child(fg)

    return(map_object)

def create_envelope_polygon(map_object, list_of_points, layer_name, line_color, fill_color, weight, text):

    # Since it is pointless to draw a box around less than 2 points check len of input
    if len(list_of_points) < 2:
        return

    # Find the edges of box
    from operator import itemgetter
    list_of_points = sorted(list_of_points,key=itemgetter(0))
    x_min = list_of_points[0]
    x_max = list_of_points[len(list_of_points)-1]

    list_of_points = sorted(list_of_points,key=itemgetter(1))
    y_min = list_of_points[0]
    y_max = list_of_points[len(list_of_points)-1]

    upper_left = (x_min[0], y_max[1])
    upper_right = (x_max[0], y_max[1])
    lower_right = (x_max[0], y_min[1])
    lower_left = (x_min[0], y_min[1])

    edges = [upper_left, upper_right, lower_right, lower_left]

    # Create feature group, add the polygon and add the feature group to the map 
    fg = folium.FeatureGroup(name=layer_name)
    fg.add_child(folium.vector_layers.Polygon(locations=edges, color=line_color, fill_color=fill_color,
                                              weight=weight, popup=(folium.Popup(text))))
    map_object.add_child(fg)

    return(map_object)