[yt-users] What does create_profile do?

Yuan Li bear0980 at gmail.com
Tue Oct 6 10:33:30 PDT 2015


Hi Greg,

Thank you! You were right! Yes, they are from the Enzo tracer particle
values. I thought that they were just the values of their host cells, and
did not know that they were CIC interpolated.

If I want to compare the different heating/cooling rates (as a function of
radius for example) calculated from the thermal history of the particles
with the rates from the simulation itself, what is the best way of doing it
so that I am comparing apples to apples?

Yuan

On Tue, Oct 6, 2015 at 8:30 AM, Greg Bryan <gbryan at astro.columbia.edu>
wrote:

> Yuan — How are you getting the density/temperature values for the tracer
> particle plot?  If it is from the Enzo tracer particle values, note that
> they are CIC interpolated from the grid, and so may differ from the cell
> values (in particular, the high-T, high-rho values you are seeing might be
> from interpolation between hot and cold cells).
>
> Greg
>
> On Oct 5, 2015, at 3:23 PM, Yuan Li <bear0980 at gmail.com> wrote:
>
> Sorry! I lied. The color range is different. Though if I make the range
> similar to the yt plot, then I do not see any particles at high densities.
>
> I should probably figure out how to make the volume weighted plot for
> particles.
>
> Yuan
>
> On Mon, Oct 5, 2015 at 2:57 PM, Yuan Li <bear0980 at gmail.com> wrote:
>
>> Hi Matt,
>>
>> Ok. I was being lazy :P. Here is a 2d histogram (without labels but the
>> range is the same as the yt plot). It still shows more points at density of
>> 1e-23 and temperature of 1e5. These should be particles in and around
>> cooling/cold clumps.
>>
>> It is 10 thousand years after the particles are injected (the first
>> particle output). Maybe somehow the particles move very very quickly from
>> the cell center to strange locations...?
>>
>> Yuan
>>
>> On Mon, Oct 5, 2015 at 2:36 PM, Matthew Turk <matthewturk at gmail.com>
>> wrote:
>>
>>> Hi Yuan,
>>>
>>> You're not applying any averaging when scattering, so you can really
>>> just get the shape, not the colors, from the particle plotting.
>>>
>>> Matt
>>>
>>> On Mon, Oct 5, 2015, 11:23 AM Yuan Li <bear0980 at gmail.com> wrote:
>>>
>>>> Hi Matt,
>>>>
>>>> Arithmetic average is what I want. It would be more meaningful to do a
>>>> volume weighted average, but am trying to compare the profile I get from
>>>> AMR simulation itself and the one I get from tracer particles, and tracer
>>>> particles do not know their cell volume (I guess I can use
>>>> find_field_value_at_point but I am worried about it taking too long for 1
>>>> million particles).
>>>>
>>>> What confuses me is that the particles give me a different profile. If
>>>> I make the phase plot of temperature vs density, it seems that there are a
>>>> lot of particles at high density and low-ish temperatures (the plot with
>>>> the blue points) that do not show up on the other plot that is made with
>>>> the simulation output. The particles are injected to the center of each
>>>> cell (the original scrip is from you I think), so I thought that every cell
>>>> should be represented on both plots the same way.
>>>>
>>>>
>>>> Yuan
>>>>
>>>>
>>>> On Mon, Oct 5, 2015 at 12:51 PM, Matthew Turk <matthewturk at gmail.com>
>>>> wrote:
>>>>
>>>>> Hi Yuan,
>>>>>
>>>>> This does do the average temperature as a function of radius, although
>>>>> note that you're weighting by ones, so it is the arithmetic average --
>>>>> i.e., unweighted by any volume or mass.  So for any AMR simulation,
>>>>> this favors the higher resolution data in a way that is
>>>>> non-conservative.
>>>>>
>>>>> On Fri, Oct 2, 2015 at 3:03 PM, Yuan Li <yuan at astro.columbia.edu>
>>>>> wrote:
>>>>> > Hi all,
>>>>> >
>>>>> > I have a really basic dumb question: what does yt do when it creates
>>>>> a
>>>>> > profile?
>>>>> >
>>>>> > For example, if I do this:
>>>>> > prof=yt.create_profile(sp,"radius",["temperature"],
>>>>> > accumulation=False,n_bins=n_bins,weight_field="ones")
>>>>> >
>>>>> > Is prof["temperature"].value the arithmetic average of the
>>>>> temperatures of
>>>>> > all the cells within each radius bin?
>>>>> >
>>>>> > The reason why I ask is because when I create a profile plot of
>>>>> > "CoolingRate" (my derived field) using yt, and compare that with the
>>>>> one I
>>>>> > create with tracer particles, they look different at low
>>>>> temperatures. Since
>>>>> > I put one particle in the center of each cell, I assume that the two
>>>>> methods
>>>>> > should give the same results. Did I make a silly mistake somewhere
>>>>> or does
>>>>> > yt do some sort of smoothing to the data?
>>>>> >
>>>>> >
>>>>> > Thank you!
>>>>> > Yuan
>>>>> >
>>>>> >
>>>>> >
>>>>> > _______________________________________________
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>>
> <0_phase_particles_color.png>
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> ----------------------------------
> Greg Bryan
> Professor of Astronomy
> Department of Astronomy, Columbia University
> 1325 Pupin Physics Laboratories, Mail Code 5246
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