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Re: Proposal for Matlab style errorbars
From: |
Ben Abbott |
Subject: |
Re: Proposal for Matlab style errorbars |
Date: |
Fri, 30 Apr 2010 07:58:14 -0400 |
On Apr 29, 2010, at 8:49 PM, Ben Abbott wrote:
> On Apr 29, 2010, at 3:37 PM, David Bateman wrote:
>
>> Ben Abbott wrote:
>>> I've modified __errplot__.m to produce Matlab style errorbars, and would
>>> like some feedback before pushing.
>>>
>>> I'm not sure how the box style error bars (#) are supposed to look. For my
>>> setup they look identical to the normal ones (i.e. "#~>" looks like "~>").
>>> Rather than duplicate the same "look", I made the box styles look like
>>> "boxes".
>>>
>>> I haven't pushed this yet, but did add some demos to errorbar.m. I
>>> recommend pulling that change to make testing/demoing this changeset easier.
>>>
>>> Of course, as an added bonus, this implementation works with the fltk
>>> backend.
>>>
>>> Ben
>>>
>>> p.s. I hope no one minds that I cc'd everyone involved in the discussion on
>>> the bug tracker.
>>>
>> As far as I can see the changes to __errplot__ itself are cosmetic.. The big
>> change is in the updata_data subfunction and with the little testing i've
>> done it seems ok. I have two points however. If we make this change to would
>> be a good idea to try and pick the same parameters using in the errorbar
>> lines in the matlab version of this. I don't have matlab. In particular is
>> the value of dx, etc the same as used in matlab? It would also make sense
>> to remove the ldata, udata, xldata and xudata from the line objects of
>> Octave, and from __go_draw_axes__ as they will no longer be used after this
>> patch. This values will only be in the hggroup itself
>>
>> Cheers
>> David
>
>
> I've verified the width of the error-bar by ...
>
> xmax = 100;
> figure(1)
> clf
> x = [0, xmax];
> y = [0, 0];
> dx = diff(x)/100;
> err = [1 1]*dx;
> errorbar (x, y, err, '-sb')
> axis equal
> axis ([-2 2 -2 2]*dx)
>
> Independent of the value for xmax, the resulting errorbar fits into a perfect
> square. I think this confirms that dx = (max(x)-min(x))/100;
>
> This matches what I saw in the figured linked to below.
>
> http://www.mathworks.se/matlabcentral/fx_files/22826/4/errorbar_tick.gif
>
> I'll remove the FIXME comment regarding the errorbar width.
>
> It occurred to me today that semilogxerr, semilogyerr, and loglogerr each
> call __errplot__ as well. I'll modify dx so that it works correctly with
> axes.scale=="log".
>
> Once I've pushed the change to __errplot__, I'll take care of
> __go_draw_axes__.m and graphics.h.in.
>
> Ben
I've pushed the change below (which supports semilogxerr, semilogyerr, and
loglogerr).
http://hg.savannah.gnu.org/hgweb/octave/rev/f0a7a72c1fbf
I plan to work on __go_draw_axes__.m and graphics.h.in this weekend.
Ben