Principle:Google deepmind Mujoco Object Name Lookup
| Knowledge Sources | |
|---|---|
| Domains | Physics_Simulation, Model_IO |
| Last Updated | 2026-02-15 06:00 GMT |
Overview
Mechanism for resolving human-readable object names to integer IDs for efficient runtime access to model elements.
Description
Object Name Lookup converts string names (e.g., "left_hand", "joint_1") into integer indices used internally by MuJoCo. The compiled mjModel stores all names in a concatenated string buffer with address arrays for O(1) lookup by ID. The reverse operation (name-to-ID) performs a linear search through the name table. This is essential for programmatic access to specific model elements.
Usage
Use to look up specific model elements by name after loading. Common for finding keyframes, sensors, actuators, or bodies by their XML-defined names.
Theoretical Basis
MuJoCo stores names as a concatenated byte array with per-type address arrays:
# Abstract name storage (not real code)
names = "world\0body1\0joint_1\0..."
body_name_adr = [0, 6, ...] # offsets into names array
# Lookup: scan body_name_adr, compare names[adr[i]] with target
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