[yt-users] Setting Units

[John Regan]

Yip that works! Thanks Britton!

On Fri, Sep 26, 2014 at 2:35 PM, Britton Smith <brittonsmith at gmail.com>
wrote:

> Hi John,
>
> I think you should be able to wipe out the units being used in the
> function and add your own by doing:
>
> return data.ds.arr(krate.d, "cm**3/s")
>
> krate.d gives you just the data array without units.
>
> Britton
>
> On Fri, Sep 26, 2014 at 7:05 AM, John Regan <johnanthonyregan at gmail.com>
> wrote:
>
>> Hi All,
>>
>> I'm having a little trouble with Units in YT-3.0.
>>
>> I want to calculate the rates for some collisional dissociations as used
>> in Enzo. The rates are fits so the dimensions are not going to be as
>> required and YT doesn't like that!
>>
>> An example script showing the problem is shown below:
>>
>> #####################################################
>> import yt
>> from yt.utilities.physical_constants import kboltz
>> import numpy as np
>>
>> def _k7(field, data): #H + e -> HM + gamma
>>     Tergs = data["Temperature"]*kboltz
>>     TeV = Tergs.convert_to_units('eV')
>>     krate = 6.77e-15*np.power(TeV, 0.8779)
>>     return krate #cm^3 s^-1
>>
>> yt.add_field(("gas", "k7rate"), units="cm**3/s", function=_k7)
>>
>> Filename = "....../RD0000/RD0000"
>>
>> ds = yt.load(Filename)
>> sp = ds.sphere('max', (100, 'kpc'))
>> print sp["k7rate"]
>> #######################################################
>>
>> The script fails with the error:
>> yt.utilities.exceptions.YTUnitConversionError: Unit dimensionalities do
>> not match. Tried to convert between eV**(8779/10000) (dim
>> (length)**(8779/5000)*(mass)**(8779/10000)/(time)**(8779/5000)) and cm**3/s
>> (dim (length)**3/(time)).
>>
>> which makes sense because the _k7() function is just a fit based on
>> temperature. Is there a way to "set" the units of k7 to be cm^3 s^-1?
>>
>> Cheers,
>> John
>>
>>
>>
>>
>>
>> _______________________________________________
>> yt-users mailing list
>> yt-users at lists.spacepope.org
>> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>>
>>
>
> _______________________________________________
> 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/20140926/90528494/attachment.htm>