Replace -inf, +inf, NaN in programs metrics by None before visualizing (#384)

When the visualizer import data from a checkpoint, this is sent to the
javascript via a response object decoded with `resp.json()` in
`fetchAndRender()` from "main.js".
 This is crashing if it does not respect fully json specs
(and NaN, Infinity are not json valid even though js objects).

This is useful for evolutions based on positive metrics to minimize (like a cost).
In that case, we want to put -metric in combined_score (which will then
be negative).
Thus an evolved program not working should be given a worse score during
evaluation. An easy way to do it is to put -inf (instead of not outputing any
metric, which will be replaced by a 0 by default by the database when
requesting a fitness).
Doing so works well during evolution (ranking the top programs as
expected), but during visualization, it was raising an error when fetching data.

Co-authored-by: Nolwen <nolwen.huet@imacs.polytechnique.fr>

Author: codelion

scripts/visualizer.py

@@ -1,9 +1,12 @@
+import math
 import os
 import json
 import glob
 import shutil
 import logging
 import re as _re
+from numbers import Number
+from typing import Optional, Any
 
 from flask import Flask, render_template, jsonify
 
@@ -63,6 +66,7 @@ def load_evolution_data(checkpoint_folder):
             if os.path.exists(prog_path):
                 with open(prog_path) as pf:
                     prog = json.load(pf)
+                    sanitize_program_for_visualization(prog)
                 prog["id"] = pid
                 prog["island"] = island_idx
                 nodes.append(prog)
@@ -84,6 +88,18 @@ def load_evolution_data(checkpoint_folder):
         "checkpoint_dir": checkpoint_folder,
     }
 
+def sanitize_program_for_visualization(program: dict[str, Any]) -> None:
+    for k, v in program["metrics"].items():
+        if not check_json_float(v):
+            program["metrics"][k] = None
+        if "parent_metrics" in program["metadata"]:
+            for k, v in program["metadata"]["parent_metrics"].items():
+                if not check_json_float(v):
+                    program["metadata"]["parent_metrics"][k] = None
+
+def check_json_float(v: Optional[float]) -> bool:
+    return isinstance(v, Number) and not (math.isinf(v) or math.isnan(v))
+
 
 @app.route("/")
 def index():