Hi Jingjing,

To add that function to the HaloCatalog analysis, you need to do the following:

hc.add_callback("sphere_field_max_recenter", "density")

Note, this callback recenters an existing sphere, so you will need to have added a sphere with:

hc.add_callback("sphere")

Make sure you add the sphere first.  Additionally, you might try the "iterative_center_of_mass" callback, which will calculate new centers by calculating the center of mass on a continually smaller sphere.  This one does not require a sphere callback and will actually write out the recentered positions.

Britton

On Mon, Mar 30, 2015 at 7:27 PM, Chen Jingjing <chenjj235@gmail.com> wrote:

Dear yt-users,

I am having a little problem on finding the exact center of a halo. I used to do

"hc = HaloCatalog(data_ds=data_ds, finder_method='hop')"

to create a halo catalog. But I think the position in the catalog is a little bit off the exact center judging from the plots I made. I need the exact center to compute the angular momentum so the off-center result could cause some problem. I tried to recenter at the maximum gas density by adding this line

"hc.sphere_field_max_recenter('density')"

But I got an error, AttributeError: 'HaloCatalog' object has no attribute 'sphere_field_max_recenter'.

Can anyone tell me what is the right way to find the center as the location of maximum gas density?

Thanks,

Jingjing

--

Jingjing Chen [ chenjj235@gmail.com ]
Department of Astronomy
Columbia University
550 West 120th Street
New York, New York 10027
Cell Phone: +1(347)5746709

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