TimestampedGeoJson not working with MultiPolygons

[Coni63]

Describe the bug
When a TimestampedGeoJson is used with basic Polygon, it is working fine but when it is multipolygons, only one sub-polygon is rendered

To Reproduce

import datetime
import numpy as np

import geojson
import folium
from folium.plugins import TimestampedGeoJson

import shapely
import shapely.ops
from shapely.geometry import MultiPolygon, Polygon, LineString

######################
#### Creation of polygons / multipolygons
######################

x1 = np.array(((0.0, 0.0), (0.0, 1.0), (1.0, 1.0), (1.0, 0.0)))

x2 = x1 * 0.1 + 1

x3 = x1 * 0.1
x3[:, 0] += 1
x3[:, 1] -= 0.1

x4 = x1 * 0.1
x4[:, 0] -= 0.1
x4[:, 1] -= 0.1

x5 = x1 * 0.1
x5[:, 1] += 1
x5[:, 0] -= 0.1

c1 = Polygon(x)
c2 = Polygon(x2)
c3 = Polygon(x3)
c4 = Polygon(x4)
c5 = Polygon(x5)

p1 = shapely.ops.unary_union([c1, c2, c3, c4, c5])
p2 = shapely.affinity.translate(p1, xoff=2, yoff=0)
p3 = shapely.affinity.translate(p1, xoff=0, yoff=2)

t1 = datetime.datetime(2023, 1, 1, 0, 0, 0)
t2 = datetime.datetime(2023, 1, 1, 6, 0, 0)
t3 = datetime.datetime(2023, 1, 1, 12, 0, 0)

data = [
    (p1, t1),
    (p2, t2),
    (p3, t3),
    (p1, t1),  # just to loop and have all 3 polygons
]

######################
#### Creation of geojson
######################

def create_geojson(data):
    features = []
    
    for (shp1, dt1), (shp2, dt2) in zip(data[:-1], data[1:]):
        feat = geojson.Feature(
            geometry=shapely.geometry.mapping(shp1),
            properties={
                "times": [1000*datetime.datetime.timestamp(dt1), 1000*datetime.datetime.timestamp(dt2)],
            }
        )
        
        features.append(feat)
        
        center1 = shp1.centroid
        center2 = shp2.centroid
        line = LineString([center1, center2])
        feat = geojson.Feature(
            geometry=shapely.geometry.mapping(line),
            properties={
                "times": [1000*datetime.datetime.timestamp(dt1), 1000*datetime.datetime.timestamp(dt2)],
            }
        )
        
        features.append(feat)
        
    return geojson.FeatureCollection(features)
    
geo = create_geojson(data)

######################
#### Rendering
######################

m = folium.Map(location=[1, 1], zoom_start=7)

folium.GeoJson(geo).add_to(m)  # works well
TimestampedGeoJson(geo, period="PT1H").add_to(m) # not working with multipolygons

m

Geojson

TimestampedGeoJson

Expected behavior
Instead of one sub-polygon, the complete multipolygon shoudl be rendered leading to the same result as folium.GeoJson

Environment (please complete the following information):

• Browser : Chrome - Windows
• Jupyter Notebook
• Python version : 3.9.13
• folium version : 0.14.0
• branca version : 0.6.0

Additional context
Add any other context about the problem here.

Possible solutions
List any solutions you may have come up with.

folium is maintained by volunteers. Can you help making a fix for this issue?

I'll try, it's a good exercice :D

[Coni63]

Sorry, in fact it's not really a bug. For multipolygon, we have to duplicate the "start" time for every polygons. The fixed code looks like:

def create_geojson(data):
    features = []
    
    for (shp1, dt1), (shp2, dt2) in zip(data[:-1], data[1:]):
        feat = geojson.Feature(
            geometry=shapely.geometry.mapping(shp1),
            properties={
                "times": [1000*datetime.datetime.timestamp(dt1)] * len(shp1) + [1000*datetime.datetime.timestamp(dt2)],  # change the line here
            }
        )
        
        features.append(feat)
        
        center1 = shp1.centroid
        center2 = shp2.centroid
        line = LineString([center1, center2])
        feat = geojson.Feature(
            geometry=shapely.geometry.mapping(line),
            properties={
                "times": [1000*datetime.datetime.timestamp(dt1), 1000*datetime.datetime.timestamp(dt2)],
            }
        )
        
        features.append(feat)
        
    return geojson.FeatureCollection(features)