datajoint/datajoint-matlab

change the interpretation of `rel & {cond1, cond2}` from `AndList` to `OrList`

Opened this issue · 8 comments

dimitri-yatsenko commented

Until now, restricting by a list (or a set) resulted in the application of all the restrictions conjunctively , i.e. rel & {cond1, cond2} was equivalent to rel & cond1 & cond2 or rel & dj.AndList(cond1, cond2).

I propose to change this interpretation to adjunction so that the above expression will be equivalent to rel & dj.OrList(cond1, cond2).

This change makes restrictions by lists logically consistent with the semijoin rel & otherRel since otherRel may be thought of as a set of conditions. Similarly, restrictions by an array of structures are also applied adjunctively.

dimitri-yatsenko commented

This may cause problems in existing code base if anyone has restricted by cell arrays intending all the conditions to be met.

eywalker commented

I agree with this change. Indeed this may break codes if it already depended on this behavior, but all in all cell list acting as or-list is more consistent with how restriction with structure array works.

ixcat commented

should be implemented with #77

ixcat commented

In our documentation, it is explained as an OR List

https://docs.datajoint.io/matlab/queries/06-Restriction.html#restriction-by-a-table

Hi @shenshan - this is noted in the block: This section documents future intended behavior in MATLAB, which is contrary to current behavior. DataJoint for MATLAB has an open issue tracking this change. which links to #128 , marked as duplicate of this issue. We should probably document both according to the version as part of the implementation plan

SchwartzNU commented

Is there a fix coming soon or a workaround for this? How can one make an OR list in MATLAB?

ixcat commented

Hello -
We're currently planning on this in the next release (3.5) - For the moment, there the following approaches:

  1. A structure array is interpreted as an OrList
  2. A struct with an array of values is interpreted as an OrList (e.g. struct('some_id', [1, 2]))
  3. String based restriction using 'or' clauses e.g. some_id=1 OR some_id=2
SchwartzNU commented

Thanks. That is very helpful. I didn't realize the 'OR' clauses worked like that. That will allow me to build OR queries with operators like '>' that are not supported in a struct.