perlquestion zing I am stuck with this complicated problem. I have a list <p>** LIST**</p> <code> substrate[s]: 3649 product[s]: 3419 3648 substrate[s]: 3645 product[s]: 3647 substrate[s]: 3659 product[s]: 3647 substrate[s]: 3675 product[s]: 3674 substrate[s]: 3674 product[s]: 3490 3489 substrate[s]: 3489 product[s]: 3490 substrate[s]: 3490 product[s]: 3485 substrate[s]: 3485 product[s]: 3486 substrate[s]: 3486 product[s]: 3488 substrate[s]: 3488 product[s]: 3487 substrate[s]: 3487 product[s]: 3877 substrate[s]: 3877 product[s]: 3419 substrate[s]: 3182 product[s]: 1875 substrate[s]: 2809 product[s]: 3182 substrate[s]: 3186 product[s]: 2809 </code> Now I have a superlist each of substrate & product as:- <p>**SUPERLIST_SUBSTRATE**</p> <code> substrate[s]: 3649 substrate[s]: 3645 substrate[s]: 3659 substrate[s]: 3675 substrate[s]: 3674 substrate[s]: 3489 substrate[s]: 3490 substrate[s]: 3485 substrate[s]: 3486 substrate[s]: 3488 substrate[s]: 3487 substrate[s]: 3877 substrate[s]: 3182 substrate[s]: 2809 substrate[s]: 3186 substrate[s]: 3675 substrate[s]: 3492 substrate[s]: 3314 substrate[s]: 3006 substrate[s]: 3049 </code> <p>**SUPERLIST_PRODUCT**</p> <code> product[s]: 3419 product[s]: 3648 product[s]: 3489 product[s]: 3647 product[s]: 3647 product[s]: 3674 product[s]: 3490 product[s]: 3490 product[s]: 3485 product[s]: 3486 product[s]: 3488 product[s]: 3487 product[s]: 3877 product[s]: 3419 product[s]: 1875 product[s]: 3182 product[s]: 2809 product[s]: 3492 product[s]: 3186 product[s]: 3492 product[s]: 1825 product[s]: 2543 </code> The superlist_product and superlist_substrate will encompass all the possible substrates & products in LIST. ie. substrate(LIST) is a subset of superlist_substrate and similarly for product(LIST). Now i want to create a SUPERARRAY as superlist_substrate(rows) X superlist_product(columns). Now parse the LIST for each substrate id one by one insert a "1" for each product id in the SUPERARRAY. For example consider first two lines of LIST <p>substrate[s]: 3649 </p> <p>product[s]: 3419 3648 </p> So for substrate id 3649 ,the row id=3649 will be selected from SUPERARRAY and a "1" will be inserted at column ids 3419 & 3648 of the SUPERARRAY. And so on for the entire LIST.Basically SUPERARRAY will be a matrix.