Re: [Matplotlib-users] Errorbars not drawn correctly in logarithmic scales

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

On Fri, Mar 9, 2012 at 1:14 PM, Wolfgang Draxinger <
wdr...@dr...> wrote:

> On Fri, 9 Mar 2012 11:19:15 -0600
> Benjamin Root <ben...@ou...> wrote:
>
> > Can I have the data you used to produce these errorbars so I can test
> > this bug?
>
> Here's the data
>
> #  Fluence.... -sigma     Signal...  -sigma       area
>      1127      48.32      9.114      10.31     0.1318
>  1.127e+04      482.9      35.96      16.15     0.4994
>  1.127e+05       4829      231.2      101.1      2.568
>  1.127e+06  4.829e+04       4631       1689      12.22
>
>
Ah, finally figured it out.  The issue is that your y-value for that error
bar is 9.114, but you want to plot error bars that are +/-10.31.  That line
gets thrown out by matplotlib because you can't plot at negative values for
log scale.  There is a trick that might work.  The set_yscale method has a
kwarg "nonposy" which could be set to "clip".  You could also try setting
to the "symlog" scale which might let you get away with a negative value.

I hope that helps!
Ben Root