Matplotlib Errorbar Caps Missing

Question

I'm attempting to create a scatter plot with errorbars in matplotlib. The following is an example of what my code looks like:

import matplotlib.pyplot as plt import numpy as np import random  x = np.linspace(1,2,10) y = np.linspace(2,3,10) err = [random.uniform(0,1) for i in range(10)]  plt.errorbar(x, y,        yerr=err,        marker='o',        color='k',        ecolor='k',        markerfacecolor='g',        label="series 2",        capsize=5,        linestyle='None') plt.show() 

The problem is the plot which is output contains no caps at all!

For what it's worth, I'm on Ubuntu 13.04, Python 2.7.5 |Anaconda 1.6.1 (64-bit)|, and Matplotlib 1.2.1.

Could this be a hidden rcparam that needs to be overwritten?

Answer 1

What worked for me was adding this (as per: How to set the line width of error bar caps, in matplotlib):

(_, caps, _) = plt.errorbar(x,y, yerr=err, capsize=20, elinewidth=3)  for cap in caps:     cap.set_color('red')     cap.set_markeredgewidth(10) 

Answer 2

It has to do with the rcParams in matplotlib. To solve it, add the following lines at the beginning of your script:

import matplotlib matplotlib.rcParams.update({'errorbar.capsize': 2}) 

It also works with plt.bar().