Automatize this process for all the x-ray diffraction files and display x-ray diagrams on asame figure with the subplot function. In addition, you should display on each diagram : 1. the file name 2. the position angle of the first peak computed with the fitting function3. vertical lines that highlights the peak positions

To automate this process for all the x-ray diffraction files, you can use a loop to iterate through each file in a directory. Here's an example code snippet in Python:

import os
import numpy as np
import matplotlib.pyplot as plt
from scipy.signal import find_peaks
from scipy.optimize import curve_fit

# define the fitting function
def gaussian(x, a, x0, sigma):
    return a * np.exp(-(x - x0) ** 2 / (2 * sigma ** 2))

# set up the subplot figure
fig, axs = plt.subplots(nrows=3, ncols=3, figsize=(12, 8))

# iterate through each file in the directory
for i, filename in enumerate(os.listdir('/path/to/directory')):
    # load the data from the file
    data = np.loadtxt(filename, skiprows=2)
    x = data[:, 0]
    y = data[:, 1]

    # find the peaks in the data
    peaks, _ = find_peaks(y, height=0.05)

    # fit a Gaussian to the first peak
    p0 = [1, x[peaks[0]], 0.1]
    popt, _ = curve_fit(gaussian, x, y, p0=p0)

    # plot the data and the fitted Gaussian
    ax = axs[i // 3, i % 3]
    ax.plot(x, y)
    ax.plot(x, gaussian(x, *popt), 'r-')
    ax.set_title(filename)
    ax.axvline(popt[1], color='gray', linestyle='--')
    for peak in peaks:
        ax.axvline(x[peak], color='gray', linestyle='--')

# add some spacing between the subplots
plt.tight_layout()

# display the figure
plt.show()

This code assumes that all the x-ray diffraction files are in the same directory. You can modify the `os.listdir` function to point to the correct directory.

The `find_peaks` function is used to find the peaks in the data. The `height` parameter determines the minimum height of the peaks. You can adjust this parameter to suit your needs.

The `curve_fit` function is used to fit a Gaussian to the first peak. The initial parameters for the Gaussian are set using the `p0` parameter. You can adjust these parameters to improve the fit.

The `ax.axvline` function is used to draw vertical lines at the position of the fitted peak and the detected peaks. The `ax.set_title` function is used to display the filename as the title of the subplot.

Hope this helps!