Help with simplifying a code + np.savetxt()

[scidam]

Your function used for plotting error-bars doesn't include any specific information, so you can just call plt.errorbar once
within plot_data:

def plot_data(energy, ydata, figname):
    fig = plt.figure()
    plt.errorbar(energy, ydata[:,0], yerr=ydata[:,1])
    plt.ylabel('x')
    plt.xlabel('y')
    plt.legend()
    plt.savefig(figname, Transparent = True)  # Transparend (first letter is uppercased? )
    plt.close('all') 

In the main code you can do the following:

# define an auxiliary variable
what_to_plot = ['area', 'offset']

for what in what_to_plot:
    plot_data(energy, locals().get(what), what + '-fig.png')  # or something similar

You can also rewrite your savetxt function in a similar way.