Customizing yt: The Configuration and Plugin Files

yt features ways to customize it to your personal preferences in terms of how much output it displays, loading custom fields, loading custom colormaps, accessing test datasets regardless of where you are in the file system, etc. This customization is done through The Configuration File and The Plugin File both of which exist in your $HOME/.yt directory.

The Configuration File

The configuration is a simple text file setting internal yt variables to custom default values to be used in future sessions.

Configuration File Format

yt will look for and recognize the file $HOME/.yt/config as a configuration file, containing several options that can be modified and adjusted to control runtime behavior. For example, a sample $HOME/.yt/config file could look like:

[yt]
loglevel = 1
maximumstoreddatasets = 10000

This configuration file would set the logging threshold much lower, enabling much more voluminous output from yt. Additionally, it increases the number of datasets tracked between instantiations of yt.

Configuration Options At Runtime

In addition to setting parameters in the configuration file itself, you can set them at runtime.

Warning

Several parameters are only accessed when yt starts up: therefore, if you want to modify any configuration parameters at runtime, you should execute the appropriate commands at the very top of your script!

This involves importing the configuration object and then setting a given parameter to be equal to a specific string. Note that even for items that accept integers, floating points and other non-string types, you must set them to be a string or else the configuration object will consider them broken.

Here is an example script, where we adjust the logging at startup:

import yt
yt.funcs.mylog.setLevel(1)

ds = yt.load("my_data0001")
ds.print_stats()

This has the same effect as setting loglevel = 1 in the configuration file. Note that a log level of 1 means that all log messages are printed to stdout. To disable logging, set the log level to 50.

Setting Configuration On the Command Line

Options can also be set directly on the command line by specifying a command-line option. For instance, if you are running the script my_script.py you can specify a configuration option with the --config argument. As an example, to lower the log level (thus making it more verbose) you can specify:

$ python2.7 my_script.py --config loglevel=1

Any configuration option specific to yt can be specified in this manner. One common configuration option would be to disable serialization:

$ python2.7 my_script.py --config serialize=False

This way projections are always re-created.

Available Configuration Options

The following external parameters are available. A number of parameters are used internally.

  • coloredlogs (default: 'False'): Should logs be colored?
  • loadfieldplugins (default: 'True'): Do we want to load the plugin file?
  • pluginfilename (default 'my_plugins.py') The name of our plugin file.
  • logfile (default: 'False'): Should we output to a log file in the filesystem?
  • loglevel (default: '20'): What is the threshold (0 to 50) for outputting log files?
  • test_data_dir (default: '/does/not/exist'): The default path the load() function searches for datasets when it cannot find a dataset in the current directory.
  • notebook_password (default: empty): If set, this will be fed to the IPython notebook created by yt notebook. Note that this should be an sha512 hash, not a plaintext password. Starting yt notebook with no setting will provide instructions for setting this.
  • serialize (default: 'False'): If true, perform automatic object serialization
  • sketchfab_api_key (default: empty): API key for https://sketchfab.com/ for uploading AMRSurface objects.
  • suppressStreamLogging (default: 'False'): If true, execution mode will be quiet.
  • stdoutStreamLogging (default: 'False'): If true, logging is directed to stdout rather than stderr
  • skip_dataset_cache (default: 'False'): If true, automatic caching of datasets is turned off.

The Plugin File

The plugin file is a means of creating custom fields, quantities, data objects, colormaps, and other code classes and objects to be used in future yt sessions without modifying the source code directly.

Note

The my_plugins.py is only parsed inside of yt.mods, so in order to use it, you must load yt with either: import yt.mods as yt or from yt.mods import *. You can tell that your plugins file is being parsed by watching for a logging message when you import yt. Note that both the yt load and iyt command line entry points invoke from yt.mods import *, so the my_plugins.py file will be parsed if you enter yt that way.

Plugin File Format

yt will look for and recognize the file $HOME/.yt/my_plugins as a plugin file, which should contain python code. If accessing yt functions and classes they will not require the yt. prefix, because of how they are loaded. It is executed at the bottom of yt.mods, and so it is provided with the entire namespace available in the module yt.mods.

For example, if I created a plugin file containing:

def _myfunc(field, data):
    return np.random.random(data["density"].shape)
add_field("random", function=_myfunc, units='auto')

then all of my data objects would have access to the field some_quantity.

You can also define other convenience functions in your plugin file. For instance, you could define some variables or functions, and even import common modules:

import os

HOMEDIR="/home/username/"
RUNDIR="/scratch/runs/"

def load_run(fn):
    if not os.path.exists(RUNDIR + fn):
        return None
    return load(RUNDIR + fn)

In this case, we’ve written load_run to look in a specific directory to see if it can find an output with the given name. So now we can write scripts that use this function:

import yt.mods as yt

my_run = yt.load_run("hotgasflow/DD0040/DD0040")

And because we have imported from yt.mods we have access to the load_run function defined in our plugin file.

Adding Custom Colormaps

To add custom Colormaps to your plugin file, you must use the make_colormap() function to generate a colormap of your choice and then add it to the plugin file. You can see an example of this in Making and Viewing Custom Colormaps. Remember that you don’t need to prefix commands in your plugin file with yt., but you’ll only be able to access the colormaps when you load the yt.mods module, not simply yt.