The bar is drawn from `y - yerr_low` to `y + yerr_upp`
ax.errorbar(x + .5,y,yerr=[[y - yerr_low],[yerr_upp -
y]],fmt='s',markersize=4)
will get you what you want.
Tom
On Fri, Feb 8, 2013 at 8:41 PM, Markus Haider <markus.hai...@uibk.ac.at> wrote:
> Hi,
>
> I think I have a problem with errorbars in a log plot. The problem is
> reproducible through the enclosed errorbar_log.py file. As you can see I
> plot a point with y = 10**(-5) and I want the errorbars drawn from
> 10**(-5.5) to 10**(-4.5) which should be symmetric in this plot but isn't.
>
> Here is the content of my errorbar_log.py file:
>
> #!/usr/bin/python
> import numpy as np
> import matplotlib.pyplot as plt
>
> fig = plt.figure()
> ax = fig.add_subplot(111)
> x = 0.0
> y = 10**(-5.0)
> yerr_low = 10**(-5.5)
> yerr_upp = 10**(-4.5)
> ax.errorbar(x,y,yerr=[[yerr_low],[yerr_upp]],fmt='o',markersize=4)
> ax.set_xlim(-1.0,1.0)
> ax.set_ylim(1E-6,1E-3)
> ax.set_yscale('log')
> plt.savefig('errorbar.png')
>
> ---------------------------------------------
>
> 10**(-5.5) = 3.162277660168379e-06
> and 10**(-4.5) = 3.1622776601683795e-05
>
> but you can see that the lower boundary is not at the calculated value.
> <http://matplotlib.1069221.n5.nabble.com/file/n40412/errorbar.png>
>
>
> Do I misunderstand the behaviour of the errorbar function or is this a bug?
>
> Cheers,
> Markus
>
>
>
> --
> View this message in context:
> http://matplotlib.1069221.n5.nabble.com/Errorbar-problem-tp40412.html
> Sent from the matplotlib - devel mailing list archive at Nabble.com.
>
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Thomas Caswell
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