[yt-users] Obtaining the current Enzo timestep from yt
trobolo dinni
trobolo.trobolo.dinni5 at gmail.com
Mon Dec 2 17:11:57 PST 2013
Hi Sam,
perfect, I understand.
I will take a look to these TimeSeries objects.
Thank you very much for the help,
Roberto
On 3 December 2013 11:59, Sam Skillman <samskillman at gmail.com> wrote:
> Hi Roberto,
>
> Unfortunately the documentation for that parameter is incorrect. It is
> not the timestep for the current step, but rather the timestep for the
> *first* step. It is a way to limit the first timestep to be small, which is
> useful for some problem types. I'll open an issue for this incorrect
> documentation.
>
> If you are analyzing a series of outputs, it may be fairly straightforward
> to calculate the dt between them using a TimeSeries object (
> http://yt-project.org/doc/analyzing/time_series_analysis.html) , but I
> don't know of a way to get this directly from any information that Enzo
> dumps out -- same goes for yt's ability to read it in.
>
> Sam
>
>
> On Mon, Dec 2, 2013 at 4:14 PM, trobolo dinni <
> trobolo.trobolo.dinni5 at gmail.com> wrote:
>
>> Hi Sam,
>>
>> referring to the Enzo documentation:
>>
>> InitialTime (internal) The time, in code units, of the current step. For
>> cosmology the units are in free-fall times at the initial epoch (see *Enzo
>> Output Formats*<http://enzo.readthedocs.org/en/latest/user_guide/EnzoOutputFormat.html#enzooutputformats>).
>> Default: generally 0, depending on problem Initialdt (internal) The
>> timestep, in code units, for the current step. For cosmology the units are
>> in free-fall times at the initial epoch (see *Enzo Output Formats*<http://enzo.readthedocs.org/en/latest/user_guide/EnzoOutputFormat.html#enzooutputformats>).
>> Default: generally 0, depending on problem
>> my understanding from this is that as Enzo does for the parameter
>> InitialTime, also Initialdt should be saved in the parameters file and
>> represents the TopGrid timestep computed by Enzo at each TopGrid cycle. So
>> when during a run the console outputs for example:
>> TopGrid dt = 7.815060e-05 time = 0.52042974743667 cycle = 7138
>>
>> the time and cycle are actually saved in the parameter file (if an output
>> is scheduled for that cycle), but dt is not, while I would expect that to
>> be saved to. Am I right?
>> dt is the thing I need because I would like to do some data analysis that
>> requires the time step (iI need to analyse the evolution of some quantities
>> over a cycle).
>>
>> Thanks, Roberto
>>
>>
>> On 3 December 2013 10:43, Sam Skillman <samskillman at gmail.com> wrote:
>>
>>> Hi Roberto,
>>>
>>> InitialTime is the current timestep in the simulation. It refers to the
>>> start time of the current timestep (as opposed to an intermediate time
>>> during the adaptive timestepping in Enzo). Initialdt is not written out to
>>> the output parameter files because it is only used for the very first step
>>> in the simulation.
>>>
>>> A shortcut that currently exists is pf.current_time, which is the same
>>> as pf.parameters['InitialTime'].
>>>
>>> I hope that helps,
>>> Sam
>>>
>>>
>>>
>>> On Mon, Dec 2, 2013 at 3:36 PM, trobolo dinni <
>>> trobolo.trobolo.dinni5 at gmail.com> wrote:
>>>
>>>> Hi Matt,
>>>>
>>>> yes, I don't know why it is not there.
>>>>
>>>> I tried with the pf.parameters function:
>>>>
>>>> *In [456]: pf.parameters['Initialdt']*
>>>>
>>>> *---------------------------------------------------------------------------*
>>>> *KeyError Traceback (most recent call
>>>> last)*
>>>>
>>>> */home/cthulhu/Repository/Python/yt
>>>> scripts/5.primary_damping_analysis.py
>>>> <http://5.primary_damping_analysis.py> in <module>()*
>>>> *----> 1 *
>>>> * 2 *
>>>> * 3 *
>>>> * 4 *
>>>> * 5 *
>>>>
>>>> *KeyError: 'Initialdt'*
>>>>
>>>> *In [458]: pf.parameters['InitialTime']*
>>>> *Out[458]: 0.52818454582493*
>>>>
>>>> but since Initialdt is not there it is not able to find it.
>>>>
>>>> Can I ask if is there a way to tell Enzo to write out the Initialdt or
>>>> should be there by default?
>>>>
>>>> Thanks,
>>>> Roberto
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On 3 December 2013 10:13, Matthew Turk <matthewturk at gmail.com> wrote:
>>>>
>>>>> Hi Roberto,
>>>>>
>>>>> On Mon, Dec 2, 2013 at 6:10 PM, trobolo dinni
>>>>> <trobolo.trobolo.dinni5 at gmail.com> wrote:
>>>>> > Dear YT users,
>>>>> >
>>>>> > I would like to ask a simple question to which I was not able to
>>>>> find a
>>>>> > solution.
>>>>> >
>>>>> > My Enzo parameters file does not have any Initialdt line saved, also
>>>>> if by
>>>>> > reading the Enzo documentation at
>>>>> > http://enzo.readthedocs.org/en/latest/parameters/initialization.htmllooks
>>>>> > like the line should be there; and I would like to obtain the current
>>>>> > timestep from the output using yt.
>>>>> >
>>>>> > I would like to ask if is there a way to do that or if there is some
>>>>> > alternative solution.
>>>>> >
>>>>> > Thanks for the help,
>>>>> > Roberto
>>>>>
>>>>> Weird that it's not there! yt can get the cycle number if it's not.
>>>>> You can see this and other parameters by looking at pf.parameters .
>>>>> You can try using the "pprint" module to make it looks nice:
>>>>>
>>>>> import pprint
>>>>> pprint.pprint(pf.parameters)
>>>>>
>>>>> -Matt
>>>>>
>>>>> >
>>>>> >
>>>>> >
>>>>> >
>>>>> >
>>>>> >
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