@agramfort, I thought None should produce the old behavior. If we go with
your proposal we need to add `False` as additional option. The second
option would be to leave None as is but link max(abs(x)) against a string
and make it default. E.g. 'maxtype' or 'maxchannel'.
With callback trick you mean that we can pass functions? What's the point
about not allowing to set a custom function? For the underlying code it
would not make a difference, right?



On Wed, Jun 12, 2013 at 9:00 PM, Alexandre Gramfort <
notifications@github.com> wrote:

> In mne/viz.py:
>
> > @@ -250,6 +276,16 @@ def plot_topo(evoked, layout, layout_scale=0.945, color=None, title=None):
> >          Everything matplotlib accepts to specify colors. If not list-like,
> >          the color specified will be repeated. If None, colors are
> >          automatically drawn.
> > +    border : str
> > +        Borders style to be used for each sensor plot.
> > +    scaling : None | dict | callable
> > +        The scaling method to be applied to channel types. If None, peak-to-peak
> > +        scaling will be used for each sensor and each channel type. If dict
> > +        a scalar value can be assigned to each sensor type, e.g.,
> > +        dict(mag=mag=1e-4). If callable a functoon is expected that returns
> > +        a float value and takes an array-like objet as argument, e.g.
> > +        lambda x: max(abs(x)). The funciton will then be applied separately
> > +        to each sensor type.
>
> I think the lambda x: max(abs(x)) should be the default when None is
> passed. I am -1 on the callable trick but maybe I just need to be
> convinced...
>
> —
> Reply to this email directly or view it on GitHub<https://github.com/mne-tools/mne-python/pull/634/files#r4664209>
> .
>