[yt-users] Problem with making SlicePlot and ProjectionPlot from new derived field

[Bili Dong - Gmail]

On Thu, Oct 5, 2017 at 3:48 PM, Bili Dong - Gmail <qobilidop at gmail.com>
wrote:

> Hi Tazkera,
>
> I think yt should be able to understand your code units and do the unit
> conversion for you, or easily configured to interpret your code units. See
> an example here
> <http://yt-project.org/docs/dev/examining/loading_data.html#tipsy-data>.
> This I feel is the better solution.
>
> But if you want to the conversion by hand, a quick fix to your code is to
> define new variables for domain width and domain center:
>
> ```
> new_domain_width = ds.domain_width*((3.086e18*6e6*0.909090893796)/(0.7))
> new_domain_center = ds.domain_center*((3.086e18*6e6*0.909090893796)/(0.7))
> yt.ProjectionPlot(ds, 'z', ('gas', 'ElectronPressure'), width=
> new_domain_width[0],
>                   center=new_domain_center)
> ```
>
> The issue with your code is that ds.domain_width and ds.domain_center are
> not fields themselves. If you try to add new fields for those constant
> values, you'll get a long list of those values as you could read from the
> error message. You could print out dd['gas', 'PhysicalDomainWidth'] or dd['gas',
> 'PhysicalDomainCenter'] in your code to see what they look like. That
> might help you understand what was wrong.
>

Sorry I was wrong. This is not true.

>
> Best,
> Bili
>
>
> On Thu, Oct 5, 2017 at 2:59 PM, tazkera haque <h.tazkera at gmail.com> wrote:
>
>> Dear yt people,
>>
>> I am working on a tipsy output file from a n-body simulation. My file
>> contains some scaled units for fields like density, coordinates, mass etc.
>> To make a physical sense of the data, I had to convert those fields units
>> to some physical units (c.g.s) and I derived new fields having cgs unit.
>> for example:
>>
>>
>>
>>
>>
>>
>>
>> *dd = ds.all_data()# derive a new domain width with conversion factor
>> (6Mpc*current_time/hubble_constant) def _NewDomainWidth(field, data):
>> return
>> ds.domain_width*((3.086e18*6e6*0.909090893796)/(0.7))ds.add_field(('gas',
>> 'PhysicalDomainWidth'), function=_NewDomainWidth, units="code_length")*
>>
>>
>>
>>
>>
>> *# derive a new domain center with conversion factor
>> (6Mpc*current_time/hubble_constant) def _NewDomainCenter(field, data):
>> return
>> ds.domain_center*((3.086e18*6e6*0.909090893796)/(0.7))ds.add_field(('gas',
>> 'PhysicalDomainCenter'), function=_NewDomainCenter, units="code_length")*
>>
>> note that here "code_length" is actually in "cm". but I could not just do
>> dd["Gas",'Coordinates'].in_units('cm'), because this conversion does not
>> take into account some constant corrections and returns the wrong length
>> magnitude.
>>
>> My goal was to make sliceplot and  projectionplot of a newly derived
>> field :
>>
>>
>>
>>
>>
>>
>>
>>
>> *# derive a new electron pressure fielddef _ElectronPressure(field,
>> data):    return
>> data['Gas','Density']*(5.49e-7)*data['Gas','Temperature']ds.add_field(('gas',
>> 'ElectronPressure'), function=_ElectronPressure,
>> units="(code_mass*K)/(code_length**3)")*
>>
>> *# integration of pressure field along line of sight*
>>
>> *yt.ProjectionPlot(ds, 'z', ('gas', 'ElectronPressure'), width =
>> dd['gas', 'PhysicalDomainWidth'],                   center = dd['gas',
>> 'PhysicalDomainCenter'] )*
>>
>>
>> *and it is returning me *
>>
>> ValueError                                Traceback (most recent call last)<ipython-input-8-fa351b6c09d1> in <module>()      1 yt.ProjectionPlot(ds, 'z', ('gas', 'ElectronPressure'), width = dd['gas', 'PhysicalDomainWidth'], ----> 2                   center = dd['gas', 'PhysicalDomainCenter'] )
>>
>> ValueError: operands could not be broadcast together with shapes (39678,) (54608,)
>>
>> Now I cannot use width =ds.domain_width and center = ds.domain_center for the same unit error. I was wondering how I can make the projectionplot for my newly derived field and newly derived domain width and domain center.
>>
>>
>>
>> Your suggestion is most welcome
>>
>>
>> Best
>>
>> Tazkera
>>
>>
>> _______________________________________________
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>> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>>
>>
>
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