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.

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

This is based on @joaquin’s answer, but a little more concise (if you just want plain error caps with no special styling):

``````distance = [1,3,7,9]
energy = [10,20,30,40]
sigma = [1,3,2,5]

plt.errorbar(distance,
energy,
sigma,
capsize=5,
elinewidth=2,
markeredgewidth=2)
`````` 