Implementation:Google deepmind Mujoco mj name2id

Knowledge Sources	MuJoCo MuJoCo API Reference
Domains	Physics_Simulation, Model_IO
Last Updated	2026-02-15 06:00 GMT

Overview

Concrete tool for looking up model element IDs by name provided by the MuJoCo C API.

Description

The mj_name2id function searches the compiled model's name table for a matching object name and returns its integer ID. It performs a linear scan through the names for the specified object type.

Usage

Call after loading a model to find specific elements by their XML-defined names. Returns -1 if the name is not found.

Code Reference

Source Location

• Repository: mujoco
• File: src/engine/engine_name.c
• Lines: 240-260

Signature

int mj_name2id(const mjModel* m, int type, const char* name);

Import

#include <mujoco/mujoco.h>

I/O Contract

Inputs

Name	Type	Required	Description
m	const mjModel*	Yes	Compiled model
type	int	Yes	Object type enum (e.g., mjOBJ_BODY, mjOBJ_JOINT, mjOBJ_KEY)
name	const char*	Yes	Object name to search for

Outputs

Name	Type	Description
return	int	Object ID (>= 0 if found, -1 if not found)

Usage Examples

#include <mujoco/mujoco.h>

mjModel* m = mj_loadXML("humanoid.xml", NULL, error, 1000);

// Find body ID by name
int torso_id = mj_name2id(m, mjOBJ_BODY, "torso");
if (torso_id >= 0) {
    printf("Torso mass: %f\n", m->body_mass[torso_id]);
}

// Find keyframe by name
int key_id = mj_name2id(m, mjOBJ_KEY, "stand");
if (key_id >= 0) {
    mj_resetDataKeyframe(m, d, key_id);
}

Related Pages

Implements Principle

• Principle:Google_deepmind_Mujoco_Object_Name_Lookup