
Dear yt-users, Hi, I'm a new user of yt. I have a question about the default 'Density' field and 'Dark_Matter_Density' field. Do they contain stellar mass? If so, how can I read and subtract stellar mass from the data? Sincerely, Y.T.

What simulation code are you working with? From the field names it sounds like Enzo data. On Wed, Oct 11, 2017 at 9:13 AM tyuta <y0u1t1a5.t@gmail.com> wrote:
Dear yt-users,
Hi, I'm a new user of yt. I have a question about the default 'Density' field and 'Dark_Matter_Density' field. Do they contain stellar mass? If so, how can I read and subtract stellar mass from the data?
Sincerely, Y.T. _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org

Yes, it's Enzo data. 2017-10-11 10:17 GMT-04:00 Nathan Goldbaum <nathan12343@gmail.com>:
What simulation code are you working with? From the field names it sounds like Enzo data.
On Wed, Oct 11, 2017 at 9:13 AM tyuta <y0u1t1a5.t@gmail.com> wrote:
Dear yt-users,
Hi, I'm a new user of yt. I have a question about the default 'Density' field and 'Dark_Matter_Density' field. Do they contain stellar mass? If so, how can I read and subtract stellar mass from the data?
Sincerely, Y.T. _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org

OK, in that case I wouldn't try to infer the stellar mass from the Dark_Matter_Density field (which does include stellar mass despite the name), instead I would define a particle filter for stars ( http://yt-project.org/doc/analyzing/filtering.html#filtering-particle-fields) and then use the new particle type defined by the filter to create a deposited particle field ( http://yt-project.org/doc/analyzing/fields.html#deposited-particle-fields). There's an example in the docs for how to do this with Tipsy data here: http://yt-project.org/doc/cookbook/constructing_data_objects.html#creating-p... For Enzo, you should use the particle_type field to create the filter - star particles in Enzo have particle_type equal to 2. Here's a short worked example: https://gist.github.com/anonymous/acd4007dbff283fc3587a47e8ba41dc3 Hope that helps! And I hope to hear more from you - your name is particularly well suited to the yt project ;) -Nathan On Wed, Oct 11, 2017 at 12:58 PM, tyuta <y0u1t1a5.t@gmail.com> wrote:
Yes, it's Enzo data.
2017-10-11 10:17 GMT-04:00 Nathan Goldbaum <nathan12343@gmail.com>:
What simulation code are you working with? From the field names it sounds like Enzo data.
On Wed, Oct 11, 2017 at 9:13 AM tyuta <y0u1t1a5.t@gmail.com> wrote:
Dear yt-users,
Hi, I'm a new user of yt. I have a question about the default 'Density' field and 'Dark_Matter_Density' field. Do they contain stellar mass? If so, how can I read and subtract stellar mass from the data?
Sincerely, Y.T. _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org

Dear Nathan, Thank you for the answer, and links to the right page of documentation! They are very helpful to me. I'm going to try a particle filter. Y.T. 2017-10-11 16:24 GMT-04:00 Nathan Goldbaum <nathan12343@gmail.com>:
OK, in that case I wouldn't try to infer the stellar mass from the Dark_Matter_Density field (which does include stellar mass despite the name), instead I would define a particle filter for stars ( http://yt-project.org/doc/analyzing/filtering.html# filtering-particle-fields) and then use the new particle type defined by the filter to create a deposited particle field ( http://yt-project.org/doc/analyzing/fields.html#deposited-particle-fields ).
There's an example in the docs for how to do this with Tipsy data here: http://yt-project.org/doc/cookbook/constructing_data_ objects.html#creating-particle-filters
For Enzo, you should use the particle_type field to create the filter - star particles in Enzo have particle_type equal to 2. Here's a short worked example:
https://gist.github.com/anonymous/acd4007dbff283fc3587a47e8ba41dc3
Hope that helps! And I hope to hear more from you - your name is particularly well suited to the yt project ;)
-Nathan
On Wed, Oct 11, 2017 at 12:58 PM, tyuta <y0u1t1a5.t@gmail.com> wrote:
Yes, it's Enzo data.
2017-10-11 10:17 GMT-04:00 Nathan Goldbaum <nathan12343@gmail.com>:
What simulation code are you working with? From the field names it sounds like Enzo data.
On Wed, Oct 11, 2017 at 9:13 AM tyuta <y0u1t1a5.t@gmail.com> wrote:
Dear yt-users,
Hi, I'm a new user of yt. I have a question about the default 'Density' field and 'Dark_Matter_Density' field. Do they contain stellar mass? If so, how can I read and subtract stellar mass from the data?
Sincerely, Y.T. _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org

Dear Nathan, The particle filter worked well and I could read the star density from the data. Thanks! Now I want to subtract stellar mass density from Dark_Matter_Density. I was trying to define a new field "only_DM", but it did not work. Could you tell me what is wrong with this? (jupiter notebook session) import yt from yt.data_objects.particle_filters import add_particle_filter def stars(pfilter, data): filter = data[(pfilter.filtered_type, "particle_type")] == 2 return filter add_particle_filter("stars", function=stars, filtered_type='io', requires=["particle_type"]) ds.add_particle_filter('stars') def only_DM(field, data): return data['Dark_Matter_Density'] - data['deposit','stars_density'] ds=yt.load(".../redshift00??") ds.add_field(("Dark_Matter_Density", "only_DM_Density"), units="kg/m**3", function=only_DM) and the error message appears: YTFieldNotFound: Could not find field '('deposit', 'stars_density')' in redshift00??. Sincerely, Y.T. 2017-10-11 16:24 GMT-04:00 Nathan Goldbaum <nathan12343@gmail.com>:
OK, in that case I wouldn't try to infer the stellar mass from the Dark_Matter_Density field (which does include stellar mass despite the name), instead I would define a particle filter for stars ( http://yt-project.org/doc/analyzing/filtering.html# filtering-particle-fields) and then use the new particle type defined by the filter to create a deposited particle field ( http://yt-project.org/doc/analyzing/fields.html#deposited-particle-fields ).
There's an example in the docs for how to do this with Tipsy data here: http://yt-project.org/doc/cookbook/constructing_data_ objects.html#creating-particle-filters
For Enzo, you should use the particle_type field to create the filter - star particles in Enzo have particle_type equal to 2. Here's a short worked example:
https://gist.github.com/anonymous/acd4007dbff283fc3587a47e8ba41dc3
Hope that helps! And I hope to hear more from you - your name is particularly well suited to the yt project ;)
-Nathan
On Wed, Oct 11, 2017 at 12:58 PM, tyuta <y0u1t1a5.t@gmail.com> wrote:
Yes, it's Enzo data.
2017-10-11 10:17 GMT-04:00 Nathan Goldbaum <nathan12343@gmail.com>:
What simulation code are you working with? From the field names it sounds like Enzo data.
On Wed, Oct 11, 2017 at 9:13 AM tyuta <y0u1t1a5.t@gmail.com> wrote:
Dear yt-users,
Hi, I'm a new user of yt. I have a question about the default 'Density' field and 'Dark_Matter_Density' field. Do they contain stellar mass? If so, how can I read and subtract stellar mass from the data?
Sincerely, Y.T. _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org

On Thu, Oct 12, 2017 at 9:33 AM, tyuta <y0u1t1a5.t@gmail.com> wrote:
Dear Nathan,
The particle filter worked well and I could read the star density from the data. Thanks! Now I want to subtract stellar mass density from Dark_Matter_Density. I was trying to define a new field "only_DM", but it did not work. Could you tell me what is wrong with this?
(jupiter notebook session) import yt from yt.data_objects.particle_filters import add_particle_filter
def stars(pfilter, data): filter = data[(pfilter.filtered_type, "particle_type")] == 2 return filter
add_particle_filter("stars", function=stars, filtered_type='io', requires=["particle_type"])
ds.add_particle_filter('stars')
def only_DM(field, data): return data['Dark_Matter_Density'] - data['deposit','stars_density']
ds=yt.load(".../redshift00??")
ds.add_field(("Dark_Matter_Density", "only_DM_Density"), units="kg/m**3", function=only_DM)
The issue might be here? I think this field needs to be named ('gas', 'only_DM_density') - the field entry in a yt field tuple is always a field type, not a field name as you've used here. You need to use the 'gas' field type because it's defined on the Enzo AMR mesh, which is usually only for gas fields. You might also want to try using a particle filter for the dark matter as well, dark matter particles have particle_type == 0. -Nathan
and the error message appears:
YTFieldNotFound: Could not find field '('deposit', 'stars_density')' in redshift00??.
Sincerely,
Y.T.
2017-10-11 16:24 GMT-04:00 Nathan Goldbaum <nathan12343@gmail.com>:
OK, in that case I wouldn't try to infer the stellar mass from the Dark_Matter_Density field (which does include stellar mass despite the name), instead I would define a particle filter for stars ( http://yt-project.org/doc/analyzing/filtering.html#filterin g-particle-fields) and then use the new particle type defined by the filter to create a deposited particle field ( http://yt-project.org/doc/analyzing/fields.html#deposited-particle-fields ).
There's an example in the docs for how to do this with Tipsy data here: http://yt-project.org/doc/cookbook/constructing_data_objects .html#creating-particle-filters
For Enzo, you should use the particle_type field to create the filter - star particles in Enzo have particle_type equal to 2. Here's a short worked example:
https://gist.github.com/anonymous/acd4007dbff283fc3587a47e8ba41dc3
Hope that helps! And I hope to hear more from you - your name is particularly well suited to the yt project ;)
-Nathan
On Wed, Oct 11, 2017 at 12:58 PM, tyuta <y0u1t1a5.t@gmail.com> wrote:
Yes, it's Enzo data.
2017-10-11 10:17 GMT-04:00 Nathan Goldbaum <nathan12343@gmail.com>:
What simulation code are you working with? From the field names it sounds like Enzo data.
On Wed, Oct 11, 2017 at 9:13 AM tyuta <y0u1t1a5.t@gmail.com> wrote:
Dear yt-users,
Hi, I'm a new user of yt. I have a question about the default 'Density' field and 'Dark_Matter_Density' field. Do they contain stellar mass? If so, how can I read and subtract stellar mass from the data?
Sincerely, Y.T. _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org

Thanks again! It worked fine. 2017-10-12 10:49 GMT-04:00 Nathan Goldbaum <nathan12343@gmail.com>:
On Thu, Oct 12, 2017 at 9:33 AM, tyuta <y0u1t1a5.t@gmail.com> wrote:
Dear Nathan,
The particle filter worked well and I could read the star density from the data. Thanks! Now I want to subtract stellar mass density from Dark_Matter_Density. I was trying to define a new field "only_DM", but it did not work. Could you tell me what is wrong with this?
(jupiter notebook session) import yt from yt.data_objects.particle_filters import add_particle_filter
def stars(pfilter, data): filter = data[(pfilter.filtered_type, "particle_type")] == 2 return filter
add_particle_filter("stars", function=stars, filtered_type='io', requires=["particle_type"])
ds.add_particle_filter('stars')
def only_DM(field, data): return data['Dark_Matter_Density'] - data['deposit','stars_density']
ds=yt.load(".../redshift00??")
ds.add_field(("Dark_Matter_Density", "only_DM_Density"), units="kg/m**3", function=only_DM)
The issue might be here? I think this field needs to be named ('gas', 'only_DM_density') - the field entry in a yt field tuple is always a field type, not a field name as you've used here. You need to use the 'gas' field type because it's defined on the Enzo AMR mesh, which is usually only for gas fields.
You might also want to try using a particle filter for the dark matter as well, dark matter particles have particle_type == 0.
-Nathan
and the error message appears:
YTFieldNotFound: Could not find field '('deposit', 'stars_density')' in redshift00??.
Sincerely,
Y.T.
2017-10-11 16:24 GMT-04:00 Nathan Goldbaum <nathan12343@gmail.com>:
OK, in that case I wouldn't try to infer the stellar mass from the Dark_Matter_Density field (which does include stellar mass despite the name), instead I would define a particle filter for stars ( http://yt-project.org/doc/analyzing/filtering.html#filterin g-particle-fields) and then use the new particle type defined by the filter to create a deposited particle field ( http://yt-project.org/doc/analyzing/fields.html#deposited-p article-fields).
There's an example in the docs for how to do this with Tipsy data here: http://yt-project.org/doc/cookbook/constructing_data_objects .html#creating-particle-filters
For Enzo, you should use the particle_type field to create the filter - star particles in Enzo have particle_type equal to 2. Here's a short worked example:
https://gist.github.com/anonymous/acd4007dbff283fc3587a47e8ba41dc3
Hope that helps! And I hope to hear more from you - your name is particularly well suited to the yt project ;)
-Nathan
On Wed, Oct 11, 2017 at 12:58 PM, tyuta <y0u1t1a5.t@gmail.com> wrote:
Yes, it's Enzo data.
2017-10-11 10:17 GMT-04:00 Nathan Goldbaum <nathan12343@gmail.com>:
What simulation code are you working with? From the field names it sounds like Enzo data.
On Wed, Oct 11, 2017 at 9:13 AM tyuta <y0u1t1a5.t@gmail.com> wrote:
Dear yt-users,
Hi, I'm a new user of yt. I have a question about the default 'Density' field and 'Dark_Matter_Density' field. Do they contain stellar mass? If so, how can I read and subtract stellar mass from the data?
Sincerely, Y.T. _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
participants (2)
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Nathan Goldbaum
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tyuta