Creating a polygon from a list of points

In [1]:

    

# 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)


    

In [2]:

    

# 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)


    

In [3]:

    

# Initialize map
my_convexhull_map = folium.Map(location=[48.5, 9.5], zoom_start=8)

# Create a convex hull polygon that contains some points
list_of_points = randome_points(amount=10, LON_min=48, LON_max=49, LAT_min=9, LAT_max=10)

create_convexhull_polygon(my_convexhull_map, list_of_points, layer_name='Example convex hull',
                        line_color='lightblue', fill_color='lightskyblue', weight=5, text='Example convex hull') 

draw_points(my_convexhull_map, list_of_points, layer_name='Example points for convex hull',
           line_color='royalblue', fill_color='royalblue', text='Example point for convex hull')

# Add layer control and show map
folium.LayerControl(collapsed=False).add_to(my_convexhull_map)
my_convexhull_map


    

    
Out[3]:

In [4]:

    

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)


    

In [5]:

    

# Initialize map
my_envelope_map = folium.Map(location=[49.5, 8.5], zoom_start=8)

# Create an envelope polygon that contains some points
list_of_points = randome_points(amount=10, LON_min=49.1, LON_max=50, LAT_min=8, LAT_max=9)

create_envelope_polygon(my_envelope_map, list_of_points, layer_name='Example envelope',
                        line_color='indianred', fill_color='red', weight=5, text='Example envelope')

draw_points(my_envelope_map, list_of_points, layer_name='Example points for envelope',
            line_color='darkred', fill_color='darkred', text='Example point for envelope')

# Add layer control and show map
folium.LayerControl(collapsed=False).add_to(my_envelope_map)
my_envelope_map


    

    
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In [6]:

    

# Initialize map
my_map_global = folium.Map(location=[48.2460683, 9.26764125], zoom_start=7)

# Create a convex hull polygon that contains some points
list_of_points = randome_points(amount=10, LON_min=48, LON_max=49, LAT_min=9, LAT_max=10)

create_convexhull_polygon(my_map_global, list_of_points, layer_name='Example convex hull',
                        line_color='lightblue', fill_color='lightskyblue', weight=5, text='Example convex hull') 

draw_points(my_map_global, list_of_points, layer_name='Example points for convex hull',
           line_color='royalblue', fill_color='royalblue', text='Example point for convex hull')

# Create an envelope polygon that contains some points
list_of_points = randome_points(amount=10, LON_min=49.1, LON_max=50, LAT_min=8, LAT_max=9)

create_envelope_polygon(my_map_global, list_of_points, layer_name='Example envelope',
                      line_color='indianred', fill_color='red', weight=5, text='Example envelope')

draw_points(my_map_global, list_of_points, layer_name='Example points for envelope',
            line_color='darkred', fill_color='darkred', text='Example point for envelope')

# Add layer control and show map
folium.LayerControl(collapsed=False).add_to(my_map_global)
my_map_global


    

    
Out[6]: