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

[Bili Dong - Gmail]

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.

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
>
>
> _______________________________________________
> yt-users mailing list
> yt-users at lists.spacepope.org
> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.spacepope.org/pipermail/yt-users-spacepope.org/attachments/20171005/d2489d1e/attachment-0001.html>