[yt-dev] [yt_analysis/yt] Rockstar Halos write_out (issue #558)

[Sam Skillman]

New issue 558: Rockstar Halos write_out
https://bitbucket.org/yt_analysis/yt/issue/558/rockstar-halos-write_out

Sam Skillman:

Currently if you load halos using LoadRockstarHalos then try to write them out, it fails due to not knowing the redshift:


```
#!python

In [14]: halos.write_out('halos.out')
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
/projects/skillman/local/src/yt-hg/yt/mods.pyc in <module>()
----> 1 halos.write_out('halos.out')

/projects/skillman/local/src/yt-hg/yt/analysis_modules/halo_finding/halo_objects.pyc in write_out(self, filename, ellipsoid_data)
   2014
   2015         f = self.comm.write_on_root(filename)
-> 2016         HaloList.write_out(self, f, ellipsoid_data)
   2017
   2018     def write_particle_lists_txt(self, prefix):

/projects/skillman/local/src/yt-hg/yt/analysis_modules/halo_finding/halo_objects.pyc in write_out(self, filename, ellipsoid_data)
   1259             f = open(filename, "w")
   1260         f.write("# HALOS FOUND WITH %s\n" % (self._name))
-> 1261         f.write("# REDSHIFT OF OUTPUT = %f\n" % (self.redshift))
   1262
   1263         if not ellipsoid_data:

AttributeError: 'LoadRockstarHalos' object has no attribute 'redshift'

```