I would like to just plot the data, that is the result from the mean (see code in bold). import numpy as np import matplotlib.pyplot as plt import glob from astropy.io import fits from astropy.wcs import WCS %matplotlib inline %matplotlib widget fig, ax = plt.subplots(figsize = (10,10)) # figsize changes the size of the plot) data_dir = glob.glob('/Users/xxxxxxxxx/Desktop/harpn_sun_release_package_ccf_2018/2018-01-18/*.fits') lams = [] fluxs = [] for file_path in data_dir:     hdul = fits.open(file_path)     data = hdul[1].data     h1 = hdul[1].header     flux = data[1]     w = WCS(h1, naxis=1, relax=False, fix=False)     lam = w.wcs_pix2world(np.arange(len(flux)), 0)[0]     lams.append(lam)     fluxs.append(flux)     ax.plot(lam,flux) mean_flux = np.mean(fluxs, axis = 0) ax.plot(lams[0], mean_flux, color = 'k', linewidth = 2) max_rv = lams[0][np.argmin(mean_flux)] ax.vlines(max_rv, np.min(fluxs), np.max(fluxs), color = 'r', linestyle='--') ax.set_xlabel('RV [km/s]') ax.set_ylabel('Normalized CCF') plt.title('CCF') plt.show() print(mean_flux)

I would like to just plot the data, that is the result from the mean (see code in bold).

import numpy as np
import matplotlib.pyplot as plt
import glob
from astropy.io import fits
from astropy.wcs import WCS
%matplotlib inline
%matplotlib widget

fig, ax = plt.subplots(figsize = (10,10)) # figsize changes the size of the plot)

data_dir = glob.glob('/Users/xxxxxxxxx/Desktop/harpn_sun_release_package_ccf_2018/2018-01-18/*.fits')

lams = []
fluxs = []

for file_path in data_dir:
    hdul = fits.open(file_path)
    data = hdul[1].data
    h1 = hdul[1].header
    flux = data[1]
    w = WCS(h1, naxis=1, relax=False, fix=False)
    lam = w.wcs_pix2world(np.arange(len(flux)), 0)[0]
    lams.append(lam)
    fluxs.append(flux)
    ax.plot(lam,flux)

mean_flux = np.mean(fluxs, axis = 0)
ax.plot(lams[0], mean_flux, color = 'k', linewidth = 2)

max_rv = lams[0][np.argmin(mean_flux)]
ax.vlines(max_rv, np.min(fluxs), np.max(fluxs), color = 'r', linestyle='--')

ax.set_xlabel('RV [km/s]')
ax.set_ylabel('Normalized CCF')

plt.title('CCF')
plt.show()

print(mean_flux)