Re: [Matplotlib-users] Problem with errorbar and log axis

[Yuxiang W. <yw...@vi...>]

If you error bars denote standard deviation of standard error of mean,
shouldn't they be non-symmetric in log scale?

Shawn

On Tue, Apr 7, 2015 at 10:11 AM, Markus Haider <mar...@ui...> wrote:
> Hi,
>
> I am trying to make an errorbar plot with a logarithmic x-axis. I have
> symmetric errors in logspace, however if I plot them, the errors are not
> symmetric anymore, as you can see in the enclosed image. Am I
> misunderstanding something or is this a bug?
>
> Thanks for your help,
> Markus
>
> Here the code I used to produce the plot:
>
> import matplotlib.pyplot as plt
>
> import numpy as np
>
> data_x_log = np.array([13.0,15.0])
>
> data_y = np.array([0.5,1])
>
> error_x_log = np.array([0.5,1.])
>
> error_x_lower = 10**(data_x_log-error_x_log)
>
> error_x_upper = 10**(data_x_log+error_x_log)
>
> fig = plt.figure()
>
> ax = fig.add_subplot(111)
>
> ax.errorbar(10**data_x_log,data_y,xerr=[error_x_lower,error_x_upper],ls='',marker='o')
>
> ax.set_xscale('log')
>
> ax.set_xlim([1E11,1E17])
>
> ax.set_ylim([0,2])
>
> plt.savefig('error.png')
>
>
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-- 
Yuxiang "Shawn" Wang
Gerling Research Lab
University of Virginia
yw...@vi...
+1 (434) 284-0836
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