Why not pull space group from file?

[CJ-Wright]

In this example why is the space group not pulled from the cif file?

[pavoljuhas]

The example mimics what happens in PDFgui. diffpy.Structure has no direct facility for space-group based crystal representation, therefore loadStructure expands the CIF to P1. The user then works with such expanded structure and can constrain it with either the CIF space group or with a lower-symmetry supergroup to allow more distortions in the model.

The second reason is that diffpy.Structure has a bit clunky API for getting the CIF space group. A better option for refining CIF structure with CIF space group is to use pyobjcryst.loadCrystal instead of loadStructure. pyobjcryst has SG-based representation so the space group would be then applied in the refinement by default.