I wanted to use xticks function 2 times on the x axis for the 2 plots but it doesn't work. I wanted to know a way to use the xticks tool to display my second axis on the top :

my_xticks2 = ['524K','574K','Interpolation \n entre 524 et 574K','Melange stochastique \n entre 524 et 574K']

import numpy  as np
import matplotlib.pyplot as plt
%matplotlib inline
from matplotlib.ticker import StrMethodFormatter

data = np.loadtxt('k_inf')
data2=np.loadtxt('k_inf-jeff33')

x = data[:, 0]
y = data[:, 1]
yerr=data[:, 2]

x2 = data2[:, 0]
y2 = data2[:, 1]
yerr2=data2[:, 2]

plt.errorbar(x, y, yerr, fmt='o', label='ENDF/B-VIII')
plt.errorbar(x2, y2, yerr2, fmt='o', label='JEFF-3.3')

my_xticks = ['550K','574K','Interpolation \n entre 550 et 574K','Melange stochastique \n entre 550 et 574K']
plt.xticks(x, my_xticks)

my_xticks2 = ['524K','574K','Interpolation \n entre 524 et 574K','Melange stochastique \n entre 524 et 574K']
plt.xticks(x2, my_xticks2)

plt.legend()

plt.gca().yaxis.set_major_formatter(StrMethodFormatter('{x:,.5f}')) # 5 decimal places
plt.ylabel('k_inf')
plt.title('plot avec ENDF/B-VIII et JEF3.3')

plt.savefig('JEF3_and_ENDFB8.pdf', dpi=300, bbox_inches='tight')

plt.show()