mne.set_eeg_reference#
- mne.set_eeg_reference(inst, ref_channels='average', copy=True, projection=False, ch_type='auto', forward=None, *, joint=False, verbose=None)[source]#
Specify which reference to use for EEG data.
Use this function to explicitly specify the desired reference for EEG. This can be either an existing electrode or a new virtual channel. This function will re-reference the data according to the desired reference.
Note that it is also possible to re-reference the signal using a Laplacian (LAP) “reference-free” transformation using the
compute_current_source_density()
function.- Parameters:
- instinstance of
Raw
|Epochs
|Evoked
Instance of Raw or Epochs with EEG channels and reference channel(s).
- ref_channels
list
ofstr
|str
Can be:
The name(s) of the channel(s) used to construct the reference.
'average'
to apply an average reference (default)'REST'
to use the Reference Electrode Standardization Technique infinity reference [1].An empty list, in which case MNE will not attempt any re-referencing of the data
- copy
bool
Specifies whether the data will be copied (True) or modified in-place (False). Defaults to True.
- projection
bool
If
ref_channels='average'
this argument specifies if the average reference should be computed as a projection (True) or not (False; default). Ifprojection=True
, the average reference is added as a projection and is not applied to the data (it can be applied afterwards with theapply_proj
method). Ifprojection=False
, the average reference is directly applied to the data. Ifref_channels
is not'average'
,projection
must be set toFalse
(the default in this case).- ch_type
list
ofstr
|str
The name of the channel type to apply the reference to. Valid channel types are
'auto'
,'eeg'
,'ecog'
,'seeg'
,'dbs'
. If'auto'
, the first channel type of eeg, ecog, seeg or dbs that is found (in that order) will be selected.New in version 0.19.
Changed in version 1.2:
list-of-str
is now supported withprojection=True
.- forwardinstance of
Forward
|None
Forward solution to use. Only used with
ref_channels='REST'
.New in version 0.21.
- joint
bool
How to handle list-of-str
ch_type
. If False (default), one projector is created per channel type. If True, one projector is created across all channel types. This is only used whenprojection=True
.New in version 1.2.
- verbose
bool
|str
|int
|None
Control verbosity of the logging output. If
None
, use the default verbosity level. See the logging documentation andmne.verbose()
for details. Should only be passed as a keyword argument.
- instinstance of
- Returns:
- instinstance of
Raw
|Epochs
|Evoked
Data with EEG channels re-referenced. If
ref_channels='average'
andprojection=True
a projection will be added instead of directly re-referencing the data.- ref_data
array
Array of reference data subtracted from EEG channels. This will be
None
ifprojection=True
orref_channels='REST'
.
- instinstance of
See also
mne.set_bipolar_reference
Convenience function for creating bipolar references.
Notes
Some common referencing schemes and the corresponding value for the
ref_channels
parameter:- Average reference:
A new virtual reference electrode is created by averaging the current EEG signal by setting
ref_channels='average'
. Bad EEG channels are automatically excluded if they are properly set ininfo['bads']
.
- A single electrode:
Set
ref_channels
to a list containing the name of the channel that will act as the new reference, for exampleref_channels=['Cz']
.
- The mean of multiple electrodes:
A new virtual reference electrode is created by computing the average of the current EEG signal recorded from two or more selected channels. Set
ref_channels
to a list of channel names, indicating which channels to use. For example, to apply an average mastoid reference, when using the 10-20 naming scheme, setref_channels=['M1', 'M2']
.
- REST
The given EEG electrodes are referenced to a point at infinity using the lead fields in
forward
, which helps standardize the signals.
If a reference is requested that is not the average reference, this function removes any pre-existing average reference projections.
During source localization, the EEG signal should have an average reference.
In order to apply a reference, the data must be preloaded. This is not necessary if
ref_channels='average'
andprojection=True
.For an average or REST reference, bad EEG channels are automatically excluded if they are properly set in
info['bads']
.
New in version 0.9.0.
References
Examples using mne.set_eeg_reference
#
Importing data from EEG devices