Fix dials.show for unknown columns of type vec3_double or miller_index

[phyy-nx]

Found by running dials.show on reflection tables modified by cctbx.xfel.merge to include a column named miller_index_asymmetric of type flex.miller_index.

[dagewa]

Looks like the right fix for now, but I note dials.show has slightly surprising behaviour for 3-vector columns. For example,

>>> from cctbx.array_family import flex
>>> foo=flex.vec3_double([(1,2,3),(3,2,1),(1,3,2)])
>>> foo.max()
(3.0, 3.0, 3.0)

The max is done on columns separately, so you get a value that is not actually present in the array. This is a bit odd if for example you are looking at Miller indices. I'm not sure how best to approach this, but I appreciate this PR is just fixing a bug, not changing that behaviour.

[phyy-nx]

Agree the max of a miller_index array doesn't seem well defined. But ya, this fixes a specific bug so merging as is. Thanks.

[rjgildea]

Looks like the right fix for now, but I note dials.show has slightly surprising behaviour for 3-vector columns. For example,

>>> from cctbx.array_family import flex
>>> foo=flex.vec3_double([(1,2,3),(3,2,1),(1,3,2)])
>>> foo.max()
(3.0, 3.0, 3.0)

The max is done on columns separately, so you get a value that is not actually present in the array. This is a bit odd if for example you are looking at Miller indices. I'm not sure how best to approach this, but I appreciate this PR is just fixing a bug, not changing that behaviour.

I'm not sure that this behaviour is entirely surprising - it is consistent with numpy array.max(axis=0), which makes sense when you're dealing with primarily columnar data:

import numpy as np
>>> a = np.array([(1,2,3),(3,2,1),(1,3,2),(1,1,1)])
>>> a.max()
3
>>> a.max(axis=0)
array([3, 3, 3])
>>> a.max(axis=1)
array([3, 3, 3, 1])

[phyy-nx]

👍