[Mne_analysis] Leadfield matrix of a specific dipole location in a label

[Alexandre Gramfort]

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hi Dip,

> I am trying to find out the sensor specific gain/leadfield matrix corresponding to some particular dipole location in a label.
>
> When I try to read the leadfield matrices from forward solution, I have a shape of (L): sensors x dipoles (i.e., 122 x 61452 in my case) where, each dipole has 3 orientations.

yes

did you read https://martinos.org/mne/dev/auto_tutorials/plot_forward.html#compute-forward-solution
?

> Is there any tracker that I can use to get the individual dipole index along with its orientation's components that I can match later on to the vertices in a given label?

fwd['src'][0]['rr'][fwd['src'][0]['vertno']]

will give you the position of dipoles

fwd['src'][0]['nn'][fwd['src'][0]['vertno']]

will give you the normal to the cortex at dipoles in the source space.

> Plus, it would be nice know whether that particular dipole is placed in left or right hemisphere. Any lead would be helpful.

left hemisphere is first in the fwd['data'] array.
wd['src'][0]['vertno'].size will tell you when you move to the right
hemisphere.

HTH
Alex