Re: [matplotlib-devel] Bug: errorbar caps require mew!=0

[Benjamin R. <ben...@ou...>]

On Tue, Apr 24, 2012 at 7:49 AM, Mike Kaufman <mc...@gm...> wrote:

> If mew=0, then the caps on errorbars are not drawn regardless of the
> setting of the "capsize" option. I don't think this should be the
> behavior, it certainly caught me off guard, since I had mew=0 set in
> rcParams.
>
> This is present as of 5b499f0180befea04fab7bfda17ba3ad7cf2380e
> (Mar 22nd master)
>
> M
>
>
This is indeed confusing and I have been meaning to do something about this
for a while now (yet another item in my todo list...).  Keep in mind that
there is actually no discrepancy.  The marker is turned onto its side.  So
the marker edge width parameter actually effects the cap's thickness.  So,
having a finite capsize, but a zero thickness should result in no cap being
drawn.

But it is totally unintuitive that mew should have anything to do with the
cap thickness and what should be done is introduce a new kwarg "capthick"
or "capheight" and eventually have it completely replace the responsibility
of mew in errorbars.

Ben Root