Merge pull request #3079 from aftersomemath:sysid-pr

PiperOrigin-RevId: 868229512
Change-Id: I790bc08fc8b0745583a2f92d9ee2c5a19ba558ea

python/mujoco/sysid/report/utils.py

@@ -0,0 +1,61 @@
+# Copyright 2026 DeepMind Technologies Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+
+"""Utility functions for report rendering."""
+
+import math
+
+from plotly import offline as plt_offline
+
+
+def plotly_script_tag() -> str:
+  """Returns an HTML <script> tag for Plotly.
+
+  currently installed in the environment.
+  """
+  plotly_js_version = plt_offline.get_plotlyjs_version()
+  return (
+      "<script"
+      f' src="https://cdn.plot.ly/plotly-{plotly_js_version}.min.js"></script>'
+  )
+
+
+def get_text_color(bg_color_hex: str) -> str:
+  """Returns 'black' or 'white' for text over a background color.
+
+  luminance of the given background hex color.
+  Useful for heatmaps and colored data tables.
+  """
+  # Convert hex to RGB
+  hex_color = bg_color_hex.lstrip("#")
+  if len(hex_color) != 6:
+    return "black"  # Fallback
+
+  rgb = tuple(int(hex_color[i : i + 2], 16) for i in (0, 2, 4))
+  r, g, b = [x / 255.0 for x in rgb]
+
+  # Calculate luminance (per WCAG guidelines)
+  # https://www.w3.org/TR/WCAG20/#relativeluminancedef
+  def lum_component(c):
+    return c / 12.92 if c <= 0.03928 else math.pow((c + 0.055) / 1.055, 2.4)
+
+  luminance = (
+      0.2126 * lum_component(r)
+      + 0.7152 * lum_component(g)
+      + 0.0722 * lum_component(b)
+  )
+
+  # Return 'black' for light backgrounds, 'white' for dark backgrounds
+  return "black" if luminance > 0.4 else "white"