How to Create a Simulator from a Config#

simulator_from_config() creates a fully configured simulated diffractometer — with no hardware connections — from a previously saved configuration file or dictionary. All real-axis positioners are soft (simulated) positioners regardless of how they were defined in the original diffractometer.

This is useful for:

Reproducing an orientation offline for data analysis.
Debugging a configuration without access to the hardware.
Computing \(hkl\) positions from a saved orientation.

Setup#

A configuration file is produced by exporting a live diffractometer:

>>> import hklpy2
>>> e4cv = hklpy2.creator(name="e4cv")
>>> # ... define sample, reflections, compute UB ...
>>> e4cv.export("e4cv-config.yml")

Create a simulator from that file#

Pass the path to the YAML file:

>>> import hklpy2
>>> sim = hklpy2.simulator_from_config("e4cv-config.yml")
>>> sim.wh()

Or pass a configuration dictionary directly:

>>> config = hklpy2.misc.load_yaml_file("e4cv-config.yml")
>>> sim = hklpy2.simulator_from_config(config)

Or pass the configuration property of an existing diffractometer to create a simulator with the same orientation — no file needed:

>>> sim = hklpy2.simulator_from_config(k6c.configuration)

The simulator preserves#

solver, geometry, and engine
real-axis names and their solver-expected order
sample(s), lattice parameters, and orientation reflections
the UB matrix
wavelength
constraints
presets

No hardware is connected — all real axes are soft positioners.

Compute positions offline#

With the orientation restored, use the simulator exactly as you would a live diffractometer:

>>> sim.forward(1, 0, 0)
>>> sim.wh()

Custom-named axes are preserved#

If the original diffractometer used custom axis names (e.g. theta instead of omega), those names are preserved in the simulator:

>>> sim = hklpy2.simulator_from_config("fourc-config.yml")
>>> sim.real_axis_names     # e.g. ['theta', 'chi', 'phi', 'ttheta']
['theta', 'chi', 'phi', 'ttheta']

Round-trip: simulator to simulator#

A simulator’s configuration can itself be used to create another simulator:

>>> sim1 = hklpy2.simulator_from_config("e4cv-config.yml")
>>> sim2 = hklpy2.simulator_from_config(sim1.configuration)