[NeXus-tech] FW: Dimensions in NXDL

[Pete Jemian]

Looks like my phone connection was terminated unexpectedly.
Was it agreed that next conference call would be in two weeks (March 4) 
at the same time?
What phone number to use (when dropping in from the sky)?

Pete

Akeroyd, FA (Freddie) wrote:
> For info
>
> -----Original Message-----
> From: Akeroyd, FA (Freddie) 
> Sent: 20 January 2009 09:02
> To: 'jemian at anl.gov'
> Subject: RE: [NeXus-tech] Dimensions in NXDL
>
> Pete,
>
> I chose dim1, dim2 etc. as they can be matched by xs:selector in xs:key
> / xs:keyref
> Unfortunately xs:selector only supports a subset of xpath expressions,
> in particular it does not support predicates and so I do not believe you
> would be able to match <dim level="1">
>
> We do not have to do dimensions checking via schema - we could leave
> that to nxvalidate itself and just write enough information into the
> schama to allow it to know what to do
>
> Regards,
>
> Freddie  
>
>
>   
>> -----Original Message-----
>> From: Pete Jemian [mailto:prjemian at gmail.com]
>> Sent: 19 January 2009 19:33
>> To: Akeroyd, FA (Freddie)
>> Subject: Re: [NeXus-tech] Dimensions in NXDL
>>
>> I've got some comments but no time to respond yet.
>> Basic thought is dim1, dim2, dim3 is not the easy way to do this (and
>> handle it later or explain it in documentation).
>> Alternative (needs more thought for sure) is <dim level="1"/> or
>> something.  Needs work and no time for that now.
>>
>> Pete
>>
>>
>>
>> Akeroyd, FA (Freddie) wrote:
>>     
>>> There is a trac ticket for this
>>> (http://trac.nexusformat.org/definitions/ticket/32) which we could
>>>       
>> use
>>     
>>> for discussion, but it would mean everybody interested would need to
>>> either join the nexus-definitions-tickets mailing list or add
>>>       
>> themselves
>>     
>>> top the CC: of the above ticket
>>>
>>> While we think about that, I'll mail a couple of initial ideas to
>>> nexus-tech
>>>
>>> What we want to be able to do is specify the dimensions of a
>>>       
> quantity
>   
>>> and be able to reference it back to other quantities to, say,
>>>       
> specify
>   
>>> that two arrays must be the same length. We may also want to be able
>>>       
>> to
>>     
>>> restrict the size or specify exactly the size of a dimension.
>>>
>>> Say in NXDL we had
>>>
>>> <field name="data">
>>> <dimensions size="3"><dim3>5</dim3> </dimensions> </field>
>>>
>>> This could specify a 3 dimensional array with the final dimension
>>>       
>> value
>>     
>>> restricted to 5
>>>
>>>
>>> <field name="data2">
>>> <dimensions ref="data" / >
>>> </field>
>>>
>>> This means data2 should have exactly the same dimensions as data1.
>>>       
>> How
>>     
>>> far do we go in allowing references to fields in other groups?
>>>
>>>
>>> <field name="data2">
>>> <dimensions size="3"><dim1 ref="data" dim="dim2" /></dimensions>
>>> </field>
>>>
>>> This means that data2 should have dim1 the same size as dim2 in data
>>>
>>>
>>> <field name="data2">
>>> <dimensions size="3"><dim1 ref="data" dim="dim2"
>>>       
>> incr="1"/></dimensions>
>>     
>>> </field>
>>>
>>> As above, but   dim1 = dim2 + 1 (so allowing for histograms etc.)
>>>
>>> These could then be converted into appropriate XML schema key/keyref
>>> combinations.
>>>
>>> Freddie
>>>
>>>
>>>       
>> --
>> ----------------------------------------------------------
>>   Pete R. Jemian, Ph.D.                <jemian at anl.gov>
>>   Beam line Controls and Data Acquisition, Group Leader
>>   Advanced Photon Source,   Argonne National Laboratory
>>   Argonne, IL  60439                   630 - 252 - 3189
>> -----------------------------------------------------------
>>      Education is the one thing for which people
>>         are willing to pay yet not receive.
>> -----------------------------------------------------------
>>
>>     
>
>   

-- 
----------------------------------------------------------
  Pete R. Jemian, Ph.D.                <jemian at anl.gov>
  Beam line Controls and Data Acquisition, Group Leader
  Advanced Photon Source,   Argonne National Laboratory
  Argonne, IL  60439                   630 - 252 - 3189
-----------------------------------------------------------
     Education is the one thing for which people
        are willing to pay yet not receive.
-----------------------------------------------------------