feat(altair): implement area-mountain-panorama

plots/area-mountain-panorama/implementations/python/altair.py

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+""" anyplot.ai
+area-mountain-panorama: Mountain Panorama Profile with Labeled Peaks
+Library: altair 6.1.0 | Python 3.14.4
+Quality: 93/100 | Created: 2026-04-25
+"""
+
+import importlib
+import os
+import sys
+
+
+# Drop script directory from sys.path so the `altair` package resolves, not this file
+sys.path[:] = [p for p in sys.path if os.path.abspath(p or ".") != os.path.dirname(os.path.abspath(__file__))]
+alt = importlib.import_module("altair")
+np = importlib.import_module("numpy")
+pd = importlib.import_module("pandas")
+
+
+# Theme tokens (chrome flips with theme; data colors stay constant)
+THEME = os.getenv("ANYPLOT_THEME", "light")
+PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
+ELEVATED_BG = "#FFFDF6" if THEME == "light" else "#242420"
+INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
+INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
+INK_MUTED = "#6B6A63" if THEME == "light" else "#A8A79F"
+BRAND = "#009E73"  # Okabe-Ito position 1 — silhouette fill (single data series)
+
+# Theme-adaptive dusk sky gradient (chrome layer above the ridgeline; spec-authorized)
+SKY_HORIZON = "#FFC58A" if THEME == "light" else "#5A3422"  # warm dusk glow at ridgeline
+SKY_MID = "#D89AA8" if THEME == "light" else "#2E1F35"  # twilight rose / deep plum
+SKY_ZENITH = "#5C5078" if THEME == "light" else "#0C0E1A"  # evening blue / night sky
+
+# Data — Wallis (Valais, CH) panorama: 16 4000-m summits along a 180° sweep
+peaks = pd.DataFrame(
+    [
+        ("Weisshorn", 4506, 9),
+        ("Zinalrothorn", 4221, 20),
+        ("Ober Gabelhorn", 4063, 30),
+        ("Dent Blanche", 4358, 42),
+        ("Matterhorn", 4478, 56),
+        ("Breithorn", 4164, 73),
+        ("Pollux", 4092, 81),
+        ("Castor", 4223, 88),
+        ("Liskamm", 4527, 97),
+        ("Monte Rosa", 4634, 109),
+        ("Strahlhorn", 4190, 122),
+        ("Rimpfischhorn", 4199, 132),
+        ("Allalinhorn", 4027, 140),
+        ("Alphubel", 4206, 148),
+        ("Täschhorn", 4491, 158),
+        ("Dom", 4545, 168),
+    ],
+    columns=["name", "elevation_m", "angle_deg"],
+)
+
+# Skyline ridge — gaussians around named peaks plus naturalistic minor ridge texture
+np.random.seed(42)
+angles = np.linspace(-2, 182, 1500)
+ridge_elev = 2950 + 110 * np.sin(angles * 0.11) + 35 * np.sin(angles * 0.43 + 1.1)
+
+for _ in range(55):
+    pos = np.random.uniform(-2, 182)
+    height = np.random.uniform(150, 480)
+    width = np.random.uniform(1.4, 3.0)
+    ridge_elev = np.maximum(ridge_elev, 2950 + height * np.exp(-((angles - pos) ** 2) / (2 * width**2)))
+
+for _, row in peaks.iterrows():
+    height = row["elevation_m"] - 2950
+    width = 2.0 + (row["elevation_m"] - 4000) * 0.0007
+    ridge_elev = np.maximum(ridge_elev, 2950 + height * np.exp(-((angles - row["angle_deg"]) ** 2) / (2 * width**2)))
+
+ridge = pd.DataFrame({"angle_deg": angles, "elevation_m": ridge_elev})
+
+# Stagger label heights so adjacent peaks don't collide; Matterhorn lifted as focal summit
+peaks = peaks.sort_values("angle_deg").reset_index(drop=True)
+LABEL_HIGH = 5800
+LABEL_LOW = 5400
+peaks["label_y"] = [LABEL_HIGH if i % 2 == 0 else LABEL_LOW for i in range(len(peaks))]
+peaks.loc[peaks["name"] == "Matterhorn", "label_y"] = 6000
+peaks["elev_label"] = peaks["elevation_m"].apply(lambda v: f"{v:.0f} m")
+
+matterhorn = peaks[peaks["name"] == "Matterhorn"]
+others = peaks[peaks["name"] != "Matterhorn"]
+
+# Shared scales / axis so all layers register on the same coordinate system
+X_SCALE = alt.Scale(domain=[0, 180])
+Y_SCALE = alt.Scale(domain=[2900, 6300])
+Y_AXIS = alt.Axis(values=[3000, 3500, 4000, 4500, 5000])
+
+# Sky — dusk vertical gradient covering the full plot area; silhouette will mask the lower half
+sky_df = pd.DataFrame({"x_min": [0], "x_max": [180], "y_min": [2900], "y_max": [6300]})
+sky = (
+    alt.Chart(sky_df)
+    .mark_rect(
+        color={
+            "x1": 0,
+            "y1": 0,
+            "x2": 0,
+            "y2": 1,
+            "gradient": "linear",
+            "stops": [
+                {"offset": 0.0, "color": SKY_ZENITH},
+                {"offset": 0.55, "color": SKY_MID},
+                {"offset": 1.0, "color": SKY_HORIZON},
+            ],
+        }
+    )
+    .encode(
+        x=alt.X("x_min:Q", scale=X_SCALE, axis=None),
+        x2="x_max:Q",
+        y=alt.Y("y_min:Q", scale=Y_SCALE, title="Elevation (m)", axis=Y_AXIS),
+        y2="y_max:Q",
+    )
+)
+
+# Silhouette — brand-green photo-like fill; ridge stroke gives the snow-edge alpenglow line
+silhouette = (
+    alt.Chart(ridge)
+    .mark_area(color=BRAND, line={"color": BRAND, "strokeWidth": 2.5}, opacity=1.0)
+    .encode(x="angle_deg:Q", y="elevation_m:Q")
+)
+
+# Leader lines from summit up to label position (with tooltip for HTML hover)
+leaders = (
+    alt.Chart(others)
+    .mark_rule(strokeWidth=1.0, opacity=0.55, color=INK_SOFT)
+    .encode(
+        x="angle_deg:Q",
+        y="elevation_m:Q",
+        y2="label_y:Q",
+        tooltip=[alt.Tooltip("name:N", title="Peak"), alt.Tooltip("elevation_m:Q", title="Elevation (m)", format=",d")],
+    )
+)
+matterhorn_leader = (
+    alt.Chart(matterhorn)
+    .mark_rule(strokeWidth=2.0, opacity=0.9, color=INK)
+    .encode(
+        x="angle_deg:Q",
+        y="elevation_m:Q",
+        y2="label_y:Q",
+        tooltip=[alt.Tooltip("name:N", title="Peak"), alt.Tooltip("elevation_m:Q", title="Elevation (m)", format=",d")],
+    )
+)
+
+# Two-line peak labels at recommended sizes (name 18, elevation 15 — meets tick-floor)
+name_labels = (
+    alt.Chart(others)
+    .mark_text(align="center", baseline="bottom", fontSize=18, fontWeight="bold", color=INK, dy=-26)
+    .encode(
+        x="angle_deg:Q",
+        y="label_y:Q",
+        text="name:N",
+        tooltip=[alt.Tooltip("name:N", title="Peak"), alt.Tooltip("elevation_m:Q", title="Elevation (m)", format=",d")],
+    )
+)
+elev_labels = (
+    alt.Chart(others)
+    .mark_text(align="center", baseline="bottom", fontSize=15, color=INK_SOFT, dy=-8)
+    .encode(
+        x="angle_deg:Q",
+        y="label_y:Q",
+        text="elev_label:N",
+        tooltip=[alt.Tooltip("name:N", title="Peak"), alt.Tooltip("elevation_m:Q", title="Elevation (m)", format=",d")],
+    )
+)
+
+# Matterhorn focal accent: notably larger label so the anchor summit reads as the composition's focus
+matterhorn_name = (
+    alt.Chart(matterhorn)
+    .mark_text(align="center", baseline="bottom", fontSize=26, fontWeight="bold", color=INK, dy=-30)
+    .encode(
+        x="angle_deg:Q",
+        y="label_y:Q",
+        text="name:N",
+        tooltip=[alt.Tooltip("name:N", title="Peak"), alt.Tooltip("elevation_m:Q", title="Elevation (m)", format=",d")],
+    )
+)
+matterhorn_elev = (
+    alt.Chart(matterhorn)
+    .mark_text(align="center", baseline="bottom", fontSize=18, fontWeight="bold", color=INK_SOFT, dy=-8)
+    .encode(
+        x="angle_deg:Q",
+        y="label_y:Q",
+        text="elev_label:N",
+        tooltip=[alt.Tooltip("name:N", title="Peak"), alt.Tooltip("elevation_m:Q", title="Elevation (m)", format=",d")],
+    )
+)
+
+chart = (
+    (sky + silhouette + leaders + matterhorn_leader + name_labels + elev_labels + matterhorn_name + matterhorn_elev)
+    .properties(
+        width=1600,
+        height=900,
+        title=alt.Title(
+            "Wallis Panorama · area-mountain-panorama · altair · anyplot.ai",
+            subtitle="Sixteen 4000-m summits along a 180° horizontal sweep, Valais Alps",
+            subtitleColor=INK_SOFT,
+            subtitleFontSize=18,
+            fontSize=28,
+            anchor="start",
+            offset=18,
+            color=INK,
+        ),
+        background=PAGE_BG,
+    )
+    .configure_view(fill=PAGE_BG, stroke=None)
+    .configure_axis(
+        domainColor=INK_SOFT,
+        tickColor=INK_SOFT,
+        gridColor=INK,
+        gridOpacity=0.0,
+        labelColor=INK_SOFT,
+        titleColor=INK,
+        labelFontSize=18,
+        titleFontSize=22,
+        tickSize=8,
+    )
+)
+
+chart.save(f"plot-{THEME}.png", scale_factor=3.0)
+chart.save(f"plot-{THEME}.html")