Hi Britton,

Thank you so much for your detailed reply! I've read documentation about Light Cone Generator, Light Ray Generator and Absorption Spectrum. I also downloaded the dataset and ran the example scripts with it. There might be two typos here:
(1) In Section "Adding Features to the Spectrum" on http://yt-project.org/doc/analysis_modules/absorption_spectrum.html gamme should be gamma.
(2) When I ran make_light_ray.py I got an error
"OSError: [Errno 2] No such file or directory: 'halo_analysis/enzo_tiny_cosmology/RD0000'"
I need to do "cp -r enzo_tiny_cosmology halo_analysis/" to make it work.

Back to my enzo parameter file, which is attached. I correct that line and know that I don't have enough dataset, so I ran plan_cosmology_splice function to it but I got the following error:

Traceback (most recent call last):
  File "plan_cosmology_splice.py", line 2, in <module>
    my_splice = CosmologySplice('enzo_run/32cube.enzo', 'Enzo')
  File "/Users/madcpf/Documents/dev_yt/src/yt-hg/yt/analysis_modules/cosmological_observation/cosmology_splice.py", line 44, in __init__
    find_outputs=find_outputs)
  File "/Users/madcpf/Documents/dev_yt/src/yt-hg/yt/convenience.py", line 131, in simulation
    find_outputs=find_outputs)
  File "/Users/madcpf/Documents/dev_yt/src/yt-hg/yt/frontends/enzo/simulation_handling.py", line 81, in __init__
    find_outputs=find_outputs)
  File "/Users/madcpf/Documents/dev_yt/src/yt-hg/yt/data_objects/time_series.py", line 350, in __init__
    self._get_all_outputs(find_outputs=find_outputs)
  File "/Users/madcpf/Documents/dev_yt/src/yt-hg/yt/frontends/enzo/simulation_handling.py", line 434, in _get_all_outputs
    self.all_outputs = self.all_time_outputs + self.all_redshift_outputs
AttributeError: 'EnzoSimulation' object has no attribute 'all_time_outputs'

Since the Enzo I need to use is a modified version of Enzo 1.5, I don't know if that's the problem and how I could fix it. Could you please give me some advice?

Also I am a little bit confused about how light ray and absorption spectrum works and have a few questions:
(1) What's the initial spectrum before any absorption? 
(2) Where does the light ray originate from? Is it shoot from a random position in the first dataset? Can we set it manually like on the surface of the box? Does it go out of the box and back into it until the next output redshift?
(3) In the output file lightraysolution.txt, what do the parameters(dl/box, Start x/y/z, End x/y/z) mean?

Sorry that I have so many questions... I wonder if there is some existing documents or paper that have a more detailed description. 

Thank you again for your help! Have a nice weekend!

Pengfei



2013/9/6 Britton Smith <brittonsmith@gmail.com>
Hi Pengfei,

The near_redshift and far_redshift are free parameters for you to set, and just control the redshift interval over which to make the light cone projection.  You might also want to look at the narrative documentation on the light cone generator, which you can find here:
http://yt-project.org/doc/analysis_modules/light_cone_generator.html
Note, that you need to use this with a simulation that made enough data outputs to connect the redshift interval you specify.  The "enzo_tiny_cosmology" dataset available at http://yt-project.org/data/ was configured to work with the light cone recipe in the cookbook, so I would suggest downloading that.

As for the error, this is happening because there is a line in your enzo parameter file that contains more than one "=" sign.  I have just submitted a pull request that fixes it, so this should be fixed soon.  In the mean time, you can simply comment out that line in your parameter file and everything should work fine.

Britton


On Fri, Sep 6, 2013 at 3:02 AM, Pengfei Chen <madcpf@gmail.com> wrote:
Hi all,

I downloaded the example script of light cone projectoin(http://yt-project.org/doc/cookbook/cosmological_analysis.html#light-cone-projection) to my laptop and changed the Enzo simulation parameter file and redshifts. But when I ran it the following error occurred:

  File "light_cone_projection.py", line 19, in <module>
    find_outputs=False)
  File "/Users/madcpf/Documents/dev_yt/src/yt-hg/yt/analysis_modules/cosmological_observation/light_cone/light_cone.py", line 158, in __init__
    find_outputs=find_outputs)
  File "/Users/madcpf/Documents/dev_yt/src/yt-hg/yt/analysis_modules/cosmological_observation/cosmology_splice.py", line 44, in __init__
    find_outputs=find_outputs)
  File "/Users/madcpf/Documents/dev_yt/src/yt-hg/yt/convenience.py", line 131, in simulation
    find_outputs=find_outputs)
  File "/Users/madcpf/Documents/dev_yt/src/yt-hg/yt/frontends/enzo/simulation_handling.py", line 81, in __init__
    find_outputs=find_outputs)
  File "/Users/madcpf/Documents/dev_yt/src/yt-hg/yt/data_objects/time_series.py", line 343, in __init__
    self._parse_parameter_file()
  File "/Users/madcpf/Documents/dev_yt/src/yt-hg/yt/frontends/enzo/simulation_handling.py", line 273, in _parse_parameter_file
    param, vals = (i.strip() for i in line.split("="))
ValueError: need more than 1 value to unpack

Does the parameters "near_redshift" and "far_redshift" in LightCone need to be the same with "CosmologyFinalRedshift" and "CosmologyInitialRedshift" in enzo parameter file?
Does anyone know how to solve this?

Thank you all!

Pengfei

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