I have two lists that look like - list_a = [('gfhr_10_dfrght_sl', None, None), ('gfhr_11_dfrght_sl', None, None), ('mnop_yxt_done', None, None), ('mnop_yxt_gd', None, None), ('frdf_yxty_syn', None, None), ('ABC_XYZ1', 2, 0), ('ABC_XYZ2', 2, 0), ('ABC_XYZ3', 2, 0), ('ABC_XYZUL', 2, 0), ('ABC_JKL1', 1, 0), ('ABC_JKL2', 1, 0)] list_b = ['ABC_XYZ1', 'ABC_XYZ2', 'ABC_XYZ3', 'ABC_XYZUL', 'mnop_yxt_done', 'mnop_yxt_gd', 'frdf_yxty_syn', 'ABC_JKL1', 'ABC_JKL2', 'DFG_OUT2_ATTgd', 'UHBCB_DFG_nvbgh'] I want a list_c that looks like - list_c = ['(2-0) ABC_XYZ1', ' (2-0) ABC_XYZ2', '(2-0) ABC_XYZ3', '(2-0) ABC_XYZUL', 'mnop_yxt_done', 'mnop_yxt_gd', 'frdf_yxty_syn', '(2-0) ABC_JKL1', '(2-0) ABC_JKL2', 'DFG_OUT2_ATTgd', 'UHBCB_DFG_nvbgh'] Basically it should replace items in list_b from items and corresponding index that are present in list_a. I have this code - for i in list_b: for j in list_a: if (i == j[0]) and (j[1] != 'None'): list_c.append(f"({j[1]}-{j[2]}) {i}") else: list_c.append(i) list_c = list(dict.fromkeys(list_c)) print(list_c) I am getting this output instead - ['ABC_XYZ1', '(2-0) ABC_XYZ1', 'ABC_XYZ2', '(2-0) ABC_XYZ2', 'ABC_XYZ3', '(2-0) ABC_XYZ3', 'ABC_XYZUL', '(2-0) ABC_XYZUL', 'mnop_yxt_done', '(None-None) mnop_yxt_done', 'mnop_yxt_gd', '(None-None) mnop_yxt_gd', 'frdf_yxty_syn', '(None-None) frdf_yxty_syn', 'ABC_JKL1', '(1-0) ABC_JKL1', 'ABC_JKL2', '(1-0) ABC_JKL2', 'DFG_OUT2_ATTgd', 'UHBCB_DFG_nvbgh'] It's appending same element again too in my code. How do I just get it once? Continue reading...