How to set the line width of error bar caps, in matplotlib?

Question

How can the line width of the error bar caps in Matplotlib be changed?

I tried the following code:

(_, caplines, _) = matplotlib.pyplot.errorbar(     data['distance'], data['energy'], yerr=data['energy sigma'],     capsize=10, elinewidth=3)  for capline in caplines:     capline.set_linewidth(10)     capline.set_color('red')  pp.draw() 

Unfortunately, this updates the color of the caps, but does not update the line width of the caps!

The resulting effect is similar to the "fat error bar lines / thin caps" in the following image:

It would be nice to have "fat" bar caps, in the case; how can this be done, in Matplotlib? Drawing the bar caps "manually", one by one with plot() would work, but a simpler alternative would be best.

Answer 1

EOL, you were very close..,

distance = [1,3,7,9] energy = [10,20,30,40] sigma = [1,3,2,5]  (_, caps, _) = plt.errorbar(distance, energy, sigma, capsize=20, elinewidth=3)  for cap in caps:     cap.set_color('red')     cap.set_markeredgewidth(10)  plt.show 

set_markeredgewidth sets the width of the cap lines.

Matplotlib objects have so many attributes that often it is difficult to remember the right ones for a given object. IPython is a very useful tool for introspecting matplotlib. I used it to analyze the properties of the 2Dlines correponding to the error cap lines and I found that and other marker properties.

Cheers