feat(altair): implement histogram-2d

plots/histogram-2d/implementations/python/altair.py

@@ -1,19 +1,28 @@
-""" pyplots.ai
+""" anyplot.ai
 histogram-2d: 2D Histogram Heatmap
-Library: altair 6.0.0 | Python 3.13.11
-Quality: 91/100 | Created: 2025-12-25
+Library: altair 6.1.0 | Python 3.13.13
+Quality: 82/100 | Updated: 2026-05-08
 """
 
+import os
+
 import altair as alt
 import numpy as np
 import pandas as pd
 
 
+# Theme tokens
+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"
+
 # Data: Bivariate normal distribution with correlation
 np.random.seed(42)
 n_points = 2000
 mean = [0, 0]
-cov = [[1, 0.7], [0.7, 1]]  # Correlation of 0.7
+cov = [[1, 0.7], [0.7, 1]]
 data = np.random.multivariate_normal(mean, cov, n_points)
 df = pd.DataFrame({"x": data[:, 0], "y": data[:, 1]})
 
@@ -22,26 +31,48 @@
     alt.Chart(df)
     .mark_rect()
     .encode(
-        x=alt.X("x:Q", bin=alt.Bin(maxbins=40), title="X Value"),
-        y=alt.Y("y:Q", bin=alt.Bin(maxbins=40), title="Y Value"),
+        x=alt.X("x:Q", bin=alt.Bin(maxbins=40), title="Variable X"),
+        y=alt.Y("y:Q", bin=alt.Bin(maxbins=40), title="Variable Y"),
         color=alt.Color(
             "count():Q",
             scale=alt.Scale(scheme="viridis"),
             title="Count",
-            legend=alt.Legend(titleFontSize=18, labelFontSize=16, gradientLength=300, gradientThickness=20),
+            legend=alt.Legend(
+                titleFontSize=18,
+                labelFontSize=16,
+                gradientLength=300,
+                gradientThickness=20,
+                fillColor=ELEVATED_BG,
+                strokeColor=INK_SOFT,
+            ),
         ),
+        tooltip=[
+            alt.Tooltip("x:Q", format=".2f", title="X Range"),
+            alt.Tooltip("y:Q", format=".2f", title="Y Range"),
+            alt.Tooltip("count():Q", title="Bin Count"),
+        ],
     )
     .properties(
-        width=1400,
-        height=800,
-        title=alt.Title("histogram-2d \u00b7 altair \u00b7 pyplots.ai", fontSize=28, anchor="middle"),
+        width=1600,
+        height=900,
+        title=alt.Title("histogram-2d · altair · anyplot.ai", fontSize=28, anchor="middle"),
+        background=PAGE_BG,
     )
-    .configure_axis(labelFontSize=18, titleFontSize=22, tickSize=8)
-    .configure_view(strokeWidth=0)
+    .configure_axis(
+        labelFontSize=18,
+        titleFontSize=22,
+        tickSize=0,
+        domainColor=INK_SOFT,
+        labelColor=INK_SOFT,
+        titleColor=INK,
+        gridColor=INK,
+        gridOpacity=0.0,
+    )
+    .configure_view(fill=PAGE_BG, stroke=INK_SOFT, strokeWidth=1)
+    .configure_title(color=INK, fontSize=28)
+    .configure_legend(fillColor=ELEVATED_BG, strokeColor=INK_SOFT, labelColor=INK_SOFT, titleColor=INK)
 )
 
-# Save as PNG (scale_factor=3 for 4200x2400, close to target 4800x2700)
-chart.save("plot.png", scale_factor=3.0)
-
-# Save as HTML for interactivity
-chart.save("plot.html")
+# Save as PNG and HTML with theme suffix
+chart.save(f"plot-{THEME}.png", scale_factor=3.0)
+chart.save(f"plot-{THEME}.html")