Update app.py

app.py

@@ -1,134 +1,98 @@
-import time
-from concurrent.futures import ThreadPoolExecutor
-from contextlib import contextmanager
+"""
+Checkout https://awesome-panel.org/resources/lonboard_dashboard/
+"""
+# pip install panel colorcet ipywidgets_bokeh geopandas palettable lonboard
+import colorcet as cc
+import geopandas as gpd
+
+from lonboard import Map, PathLayer
+from lonboard.colormap import apply_continuous_cmap
+from palettable.palette import Palette
 
-import numpy as np
 import panel as pn
-import param
-from asyncio import wrap_future
-
-class ProgressExtMod(pn.viewable.Viewer):
-    """A custom component for easy progress reporting"""
-
-    completed = param.Integer(default=0)
-    bar_color = param.String(default="info")
-    num_tasks = param.Integer(default=100, bounds=(1, None))
-
-    # @param.depends('completed', 'num_tasks')
-    @property
-    def value(self) -> int:
-        """Returns the progress value
-
-        Returns:
-            int: The progress value
-        """
-        return int(100 * (self.completed / self.num_tasks))
-
-    def reset(self):
-        """Resets the value and message"""
-        # Please note the order matters as the Widgets updates two times. One for each change
-        self.completed = 0
-
-    def __panel__(self):
-        return self.view
-
-    @param.depends("completed", "bar_color")
-    def view(self):
-        """View the widget
-        Returns:
-            pn.viewable.Viewable: Add this to your app to see the progress reported
-        """
-        if self.value:
-            return pn.widgets.Progress(
-                active=True, value=self.value, align="center", sizing_mode="stretch_width"
-            )
-        return None
-
-    @contextmanager
-    def increment(self):
-        """Increments the value
-        
-        Can be used as context manager or decorator
-        
-        Yields:
-            None: Nothing is yielded
-        """
-        self.completed += 1
-        yield
-        if self.completed == self.num_tasks:
-            self.reset()
-
-executor = ThreadPoolExecutor(max_workers=2)  # pylint: disable=consider-using-with
-progress = ProgressExtMod()
-
-
-class AsyncComponent(pn.viewable.Viewer):
-    """A component that demonstrates how to run a Blocking Background task asynchronously
-    in Panel"""
-
-    select = param.Selector(objects=range(10))
-    slider = param.Number(2, bounds=(0, 10))
-    
-    run_blocking_task = param.Event(label="RUN")
-    result = param.Number(0)
-    view = param.Parameter()
-
-    def __init__(self, **params):
-        super().__init__(**params)
-
-        self._layout = pn.Column(
-            pn.pane.Markdown("## Blocking Task Running in Background"),
-            pn.Param(
-                self,
-                parameters=["run_blocking_task", "result"],
-                widgets={"result": {"disabled": True}, "run_blocking_task": {"button_type": "primary"}},
-                show_name=False,
-            ),
-            progress,
-            pn.pane.Markdown("## Other, Non-Blocked Tasks"),
-            pn.Param(
-                self,
-                parameters=["select", "slider"],
-                widgets={"text": {"disabled": True}},
-                show_name=False,
-            ),
-            self.text
-        )
-
-    def __panel__(self):
-        return self._layout
-
-    @param.depends("slider", "select")
-    def text(self):
-        if self.select:
-            select = self.select
-        else:
-            select = 0
-        return f"{select} + {self.slider} = {select + self.slider}"
-
-    @pn.depends("run_blocking_task", watch=True)
-    async def _run_blocking_tasks(self, num_tasks=10):
-        """Runs background tasks num_tasks times"""
-        num_tasks = 20
-        progress.num_tasks = num_tasks
-        for _ in range(num_tasks):
-            future = executor.submit(self._run_blocking_task)
-            result = await wrap_future(future)
-            self._update(result)
-
-    @progress.increment()
-    def _update(self, number):
-        self.result += number
-
-    @staticmethod
-    def _run_blocking_task():
-        time.sleep(np.random.randint(1, 2))
-        return 5
-
-if pn.state.served:
-    pn.extension()
-    
-    component = AsyncComponent()
-    pn.template.FastListTemplate(
-        site="Awesome Panel", site_url="https://awesome-panel.org", title="Async Tasks", main=[component], main_layout=None, main_max_width="400px"
-    ).servable()
+
+url = "https://naciscdn.org/naturalearth/10m/cultural/ne_10m_roads_north_america.zip"
+path = "ne_10m_roads_north_america.zip"
+
+try:
+    gdf = pn.state.as_cached(
+        "ne_10m_roads_north_america", gpd.read_file, filename=path, engine="pyogrio"
+    )
+except:
+    gdf = pn.state.as_cached(
+        "ne_10m_roads_north_america", gpd.read_file, filename=url, engine="pyogrio"
+    )
+
+state_options = sorted(state for state in gdf["state"].unique() if state)
+
+
+def to_rgb(hex: str) -> list:
+    h = hex.strip("#")
+    return list(int(h[i : i + 2], 16) for i in (0, 2, 4))
+
+
+def to_palette(cmap) -> Palette:
+    """Returns the ColorCet colormap as a palettable Palette"""
+    colors = [to_rgb(item) for item in cmap]
+    return Palette(name="colorcet", map_type="colorcet", colors=colors)
+
+
+def create_map(state="California", cmap=cc.fire, alpha=0.8):
+    palette = to_palette(cmap)
+    data = gdf[gdf["state"] == state]
+    layer = PathLayer.from_geopandas(data, width_min_pixels=0.8)
+    normalized_scale_rank = (data["scalerank"] - 3) / 9
+    layer.get_color = apply_continuous_cmap(normalized_scale_rank, palette, alpha=alpha)
+    map_ = Map(layers=[layer], _height=650)
+    return map_
+
+
+description = """# lonboard
+
+A Python library for **fast, interactive geospatial vector data visualization** in Jupyter (and Panel).
+
+By utilizing new technologies like `GeoArrow` and `GeoParquet` in conjunction with GPU-based map rendering, lonboard aims to enable visualizing large geospatial datasets interactively through a simple interface."""
+
+
+# THE PANEL APP
+pn.extension("ipywidgets")
+state = pn.widgets.Select(
+    value="California",
+    options=state_options,
+    width=150,
+    name="State",
+    sizing_mode="stretch_width",
+)
+cmap = pn.widgets.ColorMap(
+    value=cc.fire,
+    options=cc.palette,
+    ncols=3,
+    swatch_width=100,
+    name="cmap by Colorcet",
+    sizing_mode="stretch_width",
+)
+alpha = pn.widgets.FloatSlider(
+    value=0.8, start=0, end=1, name="Alpha", min_width=100, sizing_mode="stretch_width"
+)
+logo = pn.pane.Image(
+    "https://github.com/developmentseed/lonboard/raw/main/assets/dalle-lonboard.jpg"
+)
+def title(state):
+    return f"# North America Roads: {state}"
+
+settings = pn.Column(state, cmap, alpha)
+description = pn.Column(pn.pane.Markdown(description, margin=5), logo)
+component = pn.Column(
+    pn.bind(title, state=state),
+    pn.panel(
+        pn.bind(create_map, state=state, cmap=cmap, alpha=alpha.param.value_throttled),
+        sizing_mode="stretch_both",
+    ),
+    sizing_mode="stretch_both",
+)
+pn.template.FastListTemplate(
+    logo="https://panel.holoviz.org/_static/logo_horizontal_dark_theme.png",
+    title="Works with LonBoard",
+    main=[component],
+    sidebar=[description, settings],
+).servable()