heatmap script

.gitignore

@@ -1 +1,3 @@
 /target
+/_reference
+/_venv

heatmap.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+"""Render a sensor dump (one bracketed row of numbers per line) as a heatmap.
+
+Usage:
+    python heatmap.py [input.txt] [-o out.png] [--cmap inferno]
+
+Each line is expected to look like:
+    [55, 192, 131, ..., 138]
+Brackets/commas are optional, so plain whitespace-separated rows also work.
+"""
+
+import argparse
+import re
+import sys
+
+
+def parse_grid(text):
+    """Parse lines of numbers into a 2D list of floats."""
+    grid = []
+    for line in text.splitlines():
+        # strip brackets and split on commas/whitespace
+        nums = re.findall(r"-?\d+(?:\.\d+)?", line)
+        if nums:
+            grid.append([float(n) for n in nums])
+    if not grid:
+        raise ValueError("No numeric data found in input")
+    width = len(grid[0])
+    if any(len(row) != width for row in grid):
+        raise ValueError("Rows have inconsistent lengths")
+    return grid
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Render a number grid as a heatmap.")
+    parser.add_argument("input", nargs="?", default="output.txt",
+                        help="input file (default: output.txt)")
+    parser.add_argument("-o", "--output",
+                        help="save figure to this path instead of showing it")
+    parser.add_argument("--cmap", default="inferno", help="matplotlib colormap")
+    parser.add_argument("--no-annot", action="store_true",
+                        help="do not print the value inside each cell")
+    args = parser.parse_args()
+
+    import matplotlib.pyplot as plt
+
+    try:
+        with open(args.input) as f:
+            grid = parse_grid(f.read())
+    except (OSError, ValueError) as e:
+        sys.exit(f"error: {e}")
+
+    rows, cols = len(grid), len(grid[0])
+
+    fig, ax = plt.subplots(figsize=(max(6, cols * 0.5), max(5, rows * 0.5)))
+    im = ax.imshow(grid, cmap=args.cmap, interpolation="nearest")
+    fig.colorbar(im, ax=ax, label="value")
+    ax.set_title(f"{args.input}  ({rows}x{cols})")
+    ax.set_xticks(range(cols))
+    ax.set_yticks(range(rows))
+
+    if not args.no_annot:
+        vmin, vmax = min(map(min, grid)), max(map(max, grid))
+        mid = (vmin + vmax) / 2
+        for r in range(rows):
+            for c in range(cols):
+                v = grid[r][c]
+                ax.text(c, r, f"{v:g}", ha="center", va="center", fontsize=6,
+                        color="white" if v < mid else "black")
+
+    fig.tight_layout()
+    if args.output:
+        fig.savefig(args.output, dpi=150)
+        print(f"saved {args.output}")
+    else:
+        plt.show()
+
+
+if __name__ == "__main__":
+    main()