import numpy as np
import matplotlib.pyplot as plt

# make data arrays
ndata = 10
x = np.linspace(0, 1, ndata)
y = np.linspace(0, 1, ndata)
yerror = np.ones(x.size)*0.1

# plot
fig = plt.figure(figsize=(12,12))
ax1 = fig.add_subplot(221)
ax1.errorbar(x, y, yerr=yerror, fmt='o')
ax1.set_title("plot all points")
ax1.set_xlim(-0.1, 1.1)
ax1.set_ylim(-0.1, 1.1)

index_plot = [1, 2, 8, 9]

ax2 = fig.add_subplot(222)
ax2.errorbar(x, y, yerr=yerror, fmt='o', markevery=index_plot)
ax2.set_title("set markevery with an array of index")
ax2.set_xlim(-0.1, 1.1)
ax2.set_ylim(-0.1, 1.1)

ax3 = fig.add_subplot(223)
ax3.errorbar(x, y, yerr=yerror, fmt='o', markevery=2, errorevery=2)
ax3.set_title("set markevery and errorevery with an integer")
ax3.set_xlim(-0.1, 1.1)
ax3.set_ylim(-0.1, 1.1)

# the following does not work
ax4 = fig.add_subplot(224)
ax4.errorbar(x, y, yerr=yerror, fmt='o', markevery=index_plot, errorevery=index_plot)
ax4.set_title("set markevery and errorevery together with an array")
ax4.set_xlim(-0.1, 1.1)
ax4.set_ylim(-0.1, 1.1)

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-43-81e2a2ded427> in <module>()
     21 
     22 ax4 = fig.add_subplot(224)
---> 23 ax4.errorbar(x, y, yerr=yerror, fmt='o', markevery=index_plot, errorevery=index_plot)
     24 ax4.set_title("set markevery and errorevery together with an array")
     25 ax4.set_xlim(-0.1, 1.1)

/usr/local/lib/python2.7/site-packages/matplotlib/axes/_axes.pyc in errorbar(self, x, y, yerr, xerr, fmt, ecolor, elinewidth, capsize, barsabove, lolims, uplims, xlolims, xuplims, errorevery, capthick, **kwargs)
   2713             xuplims = np.asarray(xuplims, bool)
   2714 
-> 2715         everymask = np.arange(len(x)) % errorevery == 0
   2716 
   2717         def xywhere(xs, ys, mask):

ValueError: operands could not be broadcast together with shapes (10,) (4,)