Add a mark argument to close_map() for marking a point with an X.

Author: Nathaniel Henry

CHANGELOG.md

@@ -9,7 +9,8 @@
   data, shows every attribute on hover, defaults to the ColorBrewer `YlGnBu`
   scale (blue = most accessible), and takes a `boundary` outline and
   semi-transparent `background` layers (e.g. a city boundary, commute isochrones,
-  or a walkshed under its POIs).
+  or a walkshed under its POIs). A `mark` argument drops an X on a point of
+  interest (e.g. a starting point).
 
 ## 1.3.0
 

src/closecity/map.py

@@ -109,6 +109,7 @@ def close_map(
     background=None,
     background_color: Any = "#3b6fb0",
     background_opacity: float = 0.3,
+    mark=None,
     buffer: float = 0.15,
 ):
     """Draw a :class:`geopandas.GeoDataFrame` from a client method as an
@@ -130,7 +131,8 @@ def close_map(
     (e.g. a city boundary from ``place_boundary``). ``background`` is one polygon
     GeoDataFrame, or a list of them, drawn as semi-transparent fills underneath
     (e.g. commute isochrones or a walkshed); ``background_color`` recycles across
-    them. Returns a plotly ``Figure``.
+    them. ``mark`` draws an "✕" on top at a ``(lon, lat)`` pair or a point
+    GeoDataFrame (e.g. a starting point). Returns a plotly ``Figure``.
     """
     try:
         import plotly.graph_objects as go
@@ -237,6 +239,22 @@ def close_map(
                 traces.append(go.Choroplethmapbox(
                     z=z, colorscale=colorscale, showscale=False, **common))
 
+    # A point marked with an "✕", drawn last so it sits on top of everything.
+    if mark is not None:
+        import geopandas as gpd
+
+        if isinstance(mark, (gpd.GeoDataFrame, gpd.GeoSeries)):
+            geom = (mark.geometry if isinstance(mark, gpd.GeoDataFrame) else mark)
+            geom = geom.to_crs(4326)
+            mlon, mlat = list(geom.x), list(geom.y)
+        else:
+            mlon, mlat = [mark[0]], [mark[1]]
+        bounds.append([min(mlon), min(mlat), max(mlon), max(mlat)])
+        traces.append(go.Scattermapbox(
+            lon=mlon, lat=mlat, mode="text", text=["✕"] * len(mlon),
+            textfont={"size": 22, "color": "#111111"},
+            hoverinfo="skip", showlegend=False))
+
     center, zoom = _center_zoom(bounds, buffer)
     fig = go.Figure(traces)
     fig.update_layout(

tests/test_map.py

@@ -47,6 +47,13 @@ def test_close_map_shades_by_fill():
     assert isinstance(fig, go.Figure)
 
 
+def test_close_map_mark():
+    import plotly.graph_objects as go
+    fig = close_map(_points(), mark = (-71.41, 41.82))
+    assert isinstance(fig, go.Figure)
+    assert fig.data[-1].mode == "text"
+
+
 def test_close_map_boundary_and_background_layers():
     import plotly.graph_objects as go
     polys = _polys()