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%matplotlib inline

Configuring MNE python

This tutorial gives a short introduction to MNE configurations.



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import os.path as op

import mne
from mne.datasets.sample import data_path

fname = op.join(data_path(), 'MEG', 'sample', 'sample_audvis_raw.fif')
raw = mne.io.read_raw_fif(fname).crop(0, 10)
original_level = mne.get_config('MNE_LOGGING_LEVEL', 'INFO')

MNE-python stores configurations to a folder called .mne in the user's home directory, or to AppData directory on Windows. The path to the config file can be found out by calling :func:mne.get_config_path.



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print(mne.get_config_path())

These configurations include information like sample data paths and plotter window sizes. Files inside this folder should never be modified manually. Let's see what the configurations contain.



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print(mne.get_config())

We see fields like "MNE_DATASETS_SAMPLE_PATH". As the name suggests, this is the path the sample data is downloaded to. All the fields in the configuration file can be modified by calling :func:mne.set_config.

Logging

Configurations also include the default logging level for the functions. This field is called "MNE_LOGGING_LEVEL".



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mne.set_config('MNE_LOGGING_LEVEL', 'INFO')
print(mne.get_config(key='MNE_LOGGING_LEVEL'))

The default value is now set to INFO. This level will now be used by default every time we call a function in MNE. We can set the global logging level for only this session by calling :func:mne.set_log_level function.



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mne.set_log_level('WARNING')
print(mne.get_config(key='MNE_LOGGING_LEVEL'))

Notice how the value in the config file was not changed. Logging level of WARNING only applies for this session. Let's see what logging level of WARNING prints for :func:mne.compute_raw_covariance.



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cov = mne.compute_raw_covariance(raw)

Nothing. This means that no warnings were emitted during the computation. If you look at the documentation of :func:mne.compute_raw_covariance, you notice the verbose keyword. Setting this parameter does not touch the configurations, but sets the logging level for just this one function call. Let's see what happens with logging level of INFO.



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cov = mne.compute_raw_covariance(raw, verbose=True)

As you see there is some info about what the function is doing. The logging level can be set to 'DEBUG', 'INFO', 'WARNING', 'ERROR' or 'CRITICAL'. It can also be set to an integer or a boolean value. The correspondence to string values can be seen in the table below. verbose=None uses the default value from the configuration file.

+----------+---------+---------+ | String | Integer | Boolean | +==========+=========+=========+ | DEBUG | 10 | | +----------+---------+---------+ | INFO | 20 | True | +----------+---------+---------+ | WARNING | 30 | False | +----------+---------+---------+ | ERROR | 40 | | +----------+---------+---------+ | CRITICAL | 50 | | +----------+---------+---------+



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mne.set_config('MNE_LOGGING_LEVEL', original_level)
print('Config value restored to: %s' % mne.get_config(key='MNE_LOGGING_LEVEL'))