def reorder_artists(df, popularity):
    # calculate lower limit
    intercept = 0.78
    slope = -5.75
    lower_limit = max(round((intercept * popularity) + slope), 0)  # in case of no popularity set limit to zero

    # pick artists that exceed lower limit but take only 10
    popular_artists = df[df['POPULARITY'] > lower_limit].index.values.tolist()[0:10]
    print(popular_artists)
    print(lower_limit)
    # generate new order if lower limit list was created with meaningful values
    if len(popular_artists) > 0 and lower_limit > 0:
        all_artists = df.index.values.tolist()
        all_artists = [x for x in all_artists if x not in popular_artists]
        df = df.loc[popular_artists + all_artists][0:25]
        return df
    else:
        df = df[0:25]