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<div class="moz-cite-prefix">On 06/01/2015 14:30, Tobias Richter
wrote:<br>
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<blockquote cite="mid:317117DB-E65B-40CA-9CC0-4251D05BDE31@esss.se"
type="cite">
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Dear all,<br class="">
<br class="">
<div class="">
<div class="">
For more complete information of what went on at the NIAC,
Here is a link to the minutes:<br class="">
<a moz-do-not-send="true"
href="http://wiki.nexusformat.org/NIAC2014_Meeting#Minutes"
class="">http://wiki.nexusformat.org/NIAC2014_Meeting#Minutes</a></div>
<div class=""><br>
</div>
</div>
</blockquote>
Happy New Year and thanks for the minutes.<br>
<br>
I can easily understand Ray's disagreement:<br>
<br>
"""<br>
Vote on proposal for NXdata axes with indices attribute only
required when required to resolve ambiguity. All in favour.
Vote on proposal with indices required as in <a
href="http://wiki.nexusformat.org/2014_axes_and_uncertainties"
title="2014 axes and uncertainties">2014_axes_and_uncertainties</a>.
Accepted: 9 in favour. Strong disagreement by Ray Osborn as adoption
is noted: "Adoption of NeXus will be hampered by additional
complexity being required unnecessarily". Ben Watts would like to
add that the default plot in NXdata should be simple and not contain
more data than required. He may make a proposal at that end in
future.
<br>
"""<br>
<br>
The indices attribute is not necessary. To get rid of ambiguities on
multidimensional data we already had the dataset attribute
"interpretation" (agreed upon values "scalar", "spectrum", "image",
"vertex" - Oak Ridge.Meeting - ) On the meeting in the vicinity of
Diamond, I already showed to you how to get rid of plotting
ambiguities by using that attribute.<br>
<br>
Below you will find how that attribute could solve most, if not all,
your cases.<br>
<br>
If you really want to visualize multidimensional data, sooner or
later you will end up with the generic solution: you will need to
specify vertices and what to be visualize at those vertices
(scalaras, spectra, images, vectors, ...). It does not help that you
avoid to write it in the file because the visualization software
*has* to generate those positions to visualize. I think you should
take into consideration the advice of people actually writing data
visualization software (Ray, myself and even Eugen was thinking
about whether the generic solution specifying points would not be
the best).<br>
<br>
I doubt I will ever add support to the new indices stuff. I can
default to the current situation where the user can specify what he
actually want to visualize.<br>
<br>
Best regards,<br>
<br>
Armando<br>
<br>
<br>
CASE 1: Indices not needed<br>
<pre>NXroot
NXentry
NXdata
@signal="data" --> *names* the default data to be visualized
@axes="x" --> *names* the default independent data
@x_indices=0
data: float[100] --> the default dependent data
x: float[100] --> the default independent data
CASE 2: Indices not needed, order is self-explanatory or example is broken.
NXroot
NXentry
NXdata
@signal="data"
@axes="time","pressure"
@pressure_indices=1
@temperature_indices=1
@time_indices=0
data: float[1000,20]
pressure: float[20]
temperature: float[20]
time: float[1000]
</pre>
<br>
CASE 3: Indices not needed. Order is enough. In case of doubt one
can always set @interpretation"="scalar" for the signal, but it is
not necessary. <br>
<pre>NXroot
NXentry
NXdata
@signal="det"
@axes="pressure","tof"
@pressure_indices=0
@tof_indices=1
det: float[100,100000]
pressure: float[100]
tof: float[100000]</pre>
CASE 4:A bit weird but can be handled with attribute interpretation
set to "scalar" to "x" and "y" and "spectrum" to "tof" and "det".<br>
<pre>NXroot
NXentry
NXdata
@signal="det"
@axes="x","y","tof"
@tof_indices=2
@x_indices=0,1
@y_indices=0,1
det: float[100,512,100000]
tof: float[100000]
x: float[100,512]
y: float[100,512]
CASE 5: det1 must have attribute interpretation set to spectrum and time set to scalar.
NXroot
NXentry
NXdata
@signal="det1"
@axes="polar_angle_demand","frame_number","."
@frame_number_indices=1
@polar_angle_rbv_indices=0,1
@time_indices=0,1
@polar_angle_demand_indices=0
polar_angle_rbv: [50,5]
det1: [50,5,1024]
polar_angle_demand: [50]
frame_number: [5]
time: [50,5]
</pre>
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