119 lines
4.3 KiB
Python
119 lines
4.3 KiB
Python
from typing import Optional, Union
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from folium.elements import JSCSSMixin
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from folium.features import GeoJson
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from folium.map import FeatureGroup
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from folium.template import Template
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from folium.utilities import JsCode, remove_empty
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class Realtime(JSCSSMixin, FeatureGroup):
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"""Put realtime data on a Leaflet map: live tracking GPS units,
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sensor data or just about anything.
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Based on: https://github.com/perliedman/leaflet-realtime
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Parameters
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----------
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source: str, dict, JsCode
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The source can be one of:
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* a string with the URL to get data from
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* a dict that is passed to javascript's `fetch` function
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for fetching the data
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* a `folium.JsCode` object in case you need more freedom.
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start: bool, default True
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Should automatic updates be enabled when layer is added
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on the map and stopped when layer is removed from the map
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interval: int, default 60000
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Automatic update interval, in milliseconds
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get_feature_id: str or JsCode, optional
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A JS function with a geojson `feature` as parameter
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default returns `feature.properties.id`
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Function to get an identifier to uniquely identify a feature over time
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update_feature: str or JsCode, optional
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A JS function with a geojson `feature` as parameter
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Used to update an existing feature's layer;
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by default, points (markers) are updated, other layers are discarded
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and replaced with a new, updated layer.
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Allows to create more complex transitions,
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for example, when a feature is updated
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remove_missing: bool, default False
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Should missing features between updates been automatically
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removed from the layer
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container: FeatureGroup or GeoJson, default GeoJson
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The container will typically be a `FeatureGroup`, `MarkerCluster` or
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`GeoJson`, but it can be anything that generates a javascript
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L.LayerGroup object, i.e. something that has the methods
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`addLayer` and `removeLayer`.
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Other keyword arguments are passed to the GeoJson layer, so you can pass
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`style`, `point_to_layer` and/or `on_each_feature`. Make sure to wrap
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Javascript functions in the JsCode class.
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Examples
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--------
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>>> from folium import JsCode
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>>> m = folium.Map(location=[40.73, -73.94], zoom_start=12)
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>>> rt = Realtime(
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... "https://raw.githubusercontent.com/python-visualization/folium-example-data/main/subway_stations.geojson",
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... get_feature_id=JsCode("(f) => { return f.properties.objectid; }"),
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... point_to_layer=JsCode(
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... "(f, latlng) => { return L.circleMarker(latlng, {radius: 8, fillOpacity: 0.2})}"
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... ),
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... interval=10000,
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... )
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>>> rt.add_to(m)
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"""
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_template = Template(
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"""
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{% macro script(this, kwargs) %}
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var {{ this.get_name() }} = L.realtime(
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{% if this.src is string or this.src is mapping -%}
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{{ this.src|tojson }},
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{% else -%}
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{{ this.src.js_code }},
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{% endif -%}
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{{ this.options | tojavascript }}
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);
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{{ this._parent.get_name() }}.addLayer(
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{{ this.get_name() }}._container
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);
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{% endmacro %}
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"""
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)
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default_js = [
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(
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"Leaflet_Realtime_js",
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"https://cdnjs.cloudflare.com/ajax/libs/leaflet-realtime/2.2.0/leaflet-realtime.js",
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)
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]
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def __init__(
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self,
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source: Union[str, dict, JsCode],
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start: bool = True,
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interval: int = 60000,
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get_feature_id: Union[JsCode, str, None] = None,
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update_feature: Union[JsCode, str, None] = None,
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remove_missing: bool = False,
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container: Optional[Union[FeatureGroup, GeoJson]] = None,
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**kwargs
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):
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super().__init__()
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self._name = "Realtime"
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self.src = source
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kwargs["start"] = start
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kwargs["interval"] = interval
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if get_feature_id is not None:
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kwargs["get_feature_id"] = JsCode(get_feature_id)
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if update_feature is not None:
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kwargs["update_feature"] = JsCode(update_feature)
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kwargs["remove_missing"] = remove_missing
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kwargs["container"] = container
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self.options = remove_empty(**kwargs)
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