Utkarsh,

Okay, thanks for that explanation.   I have some comments.

The documentation is very confusing and/or incomplete and misleading.   
Hovering over the expression box produces a popup which makes it seem as though 
t-index is the way to access things.  No real distinction is made between 
Field, Cell and Point variables  

<<The expression is evaluated and the resulting scalar value or numpy array is 
added to the output as an array>>

What??  The expression is added to the row data, which I have never seen or 
used before.  And this is PythonAnnotation, not PythonCalculator - the object 
is to display it on the screen.   So why can I only format Field data on the 
screen?
"Vertical Force: %g" %REACTZ_901    works and outputs formatted, labelled text 
on screen because it is a Field Variable
"FBFORCE1: %g" %FBFORCE[0]    prints (error) to the screen because it is a cell 
variable.   What is the point of including cell and point variables into an 
Annotation filter in a way which makes it impossible to format the annotation?  
  I'm not able to think of a situation in which this is useful.  Perhaps I'm 
not creative enough.

I couldn't find an explanation of all of this anywhere in the documentation, so 
my title for this thread stands.   I think the documentation might be expanded 
a little.   And I would suggest a new name of PythonFieldVariableAnnotation.  I 
have used it to annotate Field Variables, but I don't know how I can use 
unlabeled, unformatted Cell or Point data annotations to add value to a picture 
or animation.

Re-reading this it seems harsher than I intended.   Just my disappointment at 
not being able to Annotate Cell Values.  I appreciate your support and 
explanations, I just would like to capture this information somewhere in the 
documentation.

Thanks again,

Dennis


-----Original Message-----
From: Utkarsh Ayachit [mailto:[email protected]] 
Sent: Friday, September 09, 2016 10:54 AM
To: Dennis Conklin <[email protected]>
Cc: Paraview ([email protected]) <[email protected]>
Subject: [EXT] Re: [Paraview] Is the PythonAnnotation documentation obsolete?

Dennis,

Python Annotation only works with what's available in the current timestep. If 
you look at the "Field Data" in the SpreadSheet view, you'll see that the 
Exodus reader puts out an array with values for all timesteps for variables 
like REACTZ_901 and hence you can offset into it using t_index irrespective of 
which timestep you are at.

For Point/Cell data, you have access to the field values for all points/cells 
for the current timestep only. Thus, t_index doesn't make much sense for those 
cases. For understanding how indexing works when dealing with multblock 
datasets, I'd recommend reading Berk's blog post [1].

Hope that helps.
Utkarsh

[1] https://blog.kitware.com/improved-vtk-numpy-integration-part-5/

On Thu, Sep 8, 2016 at 2:32 PM, Dennis Conklin <[email protected]> 
wrote:
> All,
>
>
>
> I have tried to use PythonAnnotation but it only seems to work 
> properly with FieldVariables.
>
>
>
> So for instance, with field variables  of REACTZ_901 and REACTZ_902, 
> the following expressions work and display the  values as expected
>
>
>
> REACTZ_901                                displays array of values for all
> timesteps
>
> REACTZ_901[t_index]                 displays single number (no brackets)
>
> Int(REACTZ_901)                          (error)
>
> Int(REACTZ_901[t_index]            displays truncated integer value (no
> brackets)
>
>
>
> To try to work with CellData I have made an ExtractSelection of a 
> single Cell.  I have a Cell variable of FBFORCE1
>
> I want to use PythonAnnotation to print out the FBFORCE1 for that cell 
> over time (with formatting)
>
>
>
> FBFORCE1                                      [VTKArray([154.2])]  shouldn’t
> this have a value for each timestep?
>
> FBFORCE1[t_index]                       (error)
>
> FBFORCE1[0]                                  [ 154.2]
>
> FBFORCE1[1]                                  (error)
>
> Int(FBFORCE1)                                (error)
>
> Int(FBFORCE1[0])                           (error)
>
>
>
> 2nd try – Ran PythonAnnotation on an entire file – many cells, with 
> following results
>
> FBFORCE1                                       VTKArray([ value1, value2
> ………value_final]) – seems like 1 value per timestep (shouldn’t there be 
> array of # of cells by # of timesteps?
>
>
>
> FBFORCE1[t_index]                       [131.4]  -  again- should be array
> of # of cells? Which cell is this
>
> FBFORCE1[t_index][0]                   (error)
>
> Int(FBFORCE1[t_index])                 error)
>
>
>
> So it seems that Field Variables are numpy-friendly in that formatting 
> works with them, while Cell Variables are still VTK Array variables 
> and not numpy-friendly.
>
>
>
> It’s possible that I am completely missing something here, but it 
> seems Cell Variables are not very useable in the PythonAnnotation.  Is 
> there a way for me to Annotate with individual cell values, either by 
> running PythonAnnotation on a single cell, or by manipulating the 
> variables which are available in the filter?
>
>
>
> At this point I don’t know why Cell and Point Variables are included 
> in the filter since I can only figure out how to use Field Variables
>
>
>
> Thanks for any hints
>
>
>
> Dennis
>
>
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