Re: [Matplotlib-users] vertical padding in legend

[Eric F. <ef...@ha...>]

Christopher Brown wrote:
> Sorry, meant to send to the list...
> 
> Hi Eric,
> 
> EF> > the vertical padding is too large in the first
> EF> > legend, and too small in the second.
> EF>
> EF> This looks to me like a design flaw: the pad is "fractional"
> EF> (fraction  of legend box size), when logically it should be in
> EF> something like units  of legend text height, or possibly in points.
> EF> This might be easy enough  to change, although for backwards
> EF> compatibility we would need to use a  new kwarg.
> 
> Could you point me to the function where this change needs to occur? I'd
> like to hack at it, because I have deadline for a figure. I'm searching
> around in legend.py, is that where I should be looking?

Yes, that is the place.  In principle it should be easy to fix, and 
maybe it is...or maybe it isn't.  It will certainly have to do with 
transforms, and using the right one the right way in the right place.

> 
> Also, why would a new kwarg be necessary? If the change simply means
> that the vertical padding is computed correctly, how would that break
> backward compatibility?
> 

Because the workaround is to fiddle with the pad value for each 
individual case to make the plot look right, so scripts with that 
workaround would fail if suddenly the pad kwarg were to be interpreted 
in sane units.

The new kwarg could be "pad_units", as a modifier for the pad kwarg.  Or 
something like a "padpoints" kwarg could be introduced as an overlapping 
replacement. Or we could just break the API and hope it doesn't cause 
too much trouble.  I am not sure what the right approach is in this 
case.  I'm also not sure whether this is the only place where a "pad" 
value is still in poorly-chosen units. There was another such case that 
we fixed quite a long time ago.

Eric