I am trying to simplify this code, in python,  so that I do not have to list each file separately.   Is there a way that I can access the FITS files via a folder on my Desktop to produce one plot of several FITS files.     import numpy as np import matplotlib.pyplot as plt from astropy.io import fits from astropy.wcs import WCS %matplotlib inline %matplotlib widget plt.figure(figsize=(10,10)) legends = [] def plot_fits_file(file_path):     # used this data to test ----------     # lam = np.random.random(100)     # flux = np.random.random(100)     # --------------------     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]     plt.plot(lam, flux)     plt.ylim(0, )     plt.xlabel('RV[km/s]')     plt.ylabel('Normalized CCF')     legends.append(file_path)  spec_list = [     '~/Desktop/r.HARPN.2018-01-18T14:25:36.145_CCF_A.fits',     '~/Desktop/r.HARPN.2018-01-18T14:20:10.645_CCF_A.fits',     '~/Desktop/r.HARPN.2018-01-18T14:31:00.875_CCF_A.fits',     '~/Desktop/r.HARPN.2018-01-18T14:36:26.373_CCF_A.fits'] for file_path in spec_list:     plot_fits_file(file_path) plt.show()

I am trying to simplify this code, in python,  so that I do not have to list each file separately.  

Is there a way that I can access the FITS files via a folder on my Desktop to produce one plot of several FITS files.

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

plt.figure(figsize=(10,10))
legends = []

def plot_fits_file(file_path):
    # used this data to test ----------
    # lam = np.random.random(100)
    # flux = np.random.random(100)
    # --------------------

    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]

    plt.plot(lam, flux)
    plt.ylim(0, )
    plt.xlabel('RV[km/s]')
    plt.ylabel('Normalized CCF')
    legends.append(file_path) 

spec_list = [
    '~/Desktop/r.HARPN.2018-01-18T14:25:36.145_CCF_A.fits',
    '~/Desktop/r.HARPN.2018-01-18T14:20:10.645_CCF_A.fits',
    '~/Desktop/r.HARPN.2018-01-18T14:31:00.875_CCF_A.fits',
    '~/Desktop/r.HARPN.2018-01-18T14:36:26.373_CCF_A.fits']

for file_path in spec_list:
    plot_fits_file(file_path)

plt.show()