I have multiple savings accounts, some of which I want to partition into mutiple virtual "subaccounts" that don't merit their own savings account. I want to use org-mode tables to keep track how much money is each subaccount. Given the following table: #+TBLNAME: trans-150925 | ! | Amount | From | To | Subacct | |---+--------+------------+------------+-------------| | | 50 | Short Term | Inbox | Bond | | | 200 | Inbox | Short Term | Bond | | | 120 | Gifts | Inbox | Baby Gifts | | | 75 | Short Term | Inbox | Furnishings | In this example, I have accounts "Inbox", "Short Term", and "Gifts". Of these accounts, "Short Term" has two subaccounts "Bond" and "Furnishings", and "Gifts" has a subaccount "Baby Gifts". I want to create a function that given a subaccount name, calculates the net amount to be withdrawn/deposited to the subaccount. Note that "Inbox" doesn't have any subaccounts, which I want to use to determine if a given transaction is a withdrawal or deposit to the subaccount. I have created the following two functions to implement this: (defun sbr/org-lookup-trans (category date s-name r-name) (let* ((table (concat "trans-" date)) (s-range (format "@I%s..@>%s" s-name s-name)) (s-col (org-table-get-remote table s-range)) (r-range (format "@I%s..@>%s" r-name r-name)) (r-col (org-table-get-remote table r-range))) (org-lookup-all category s-col r-col))) (defun sbr/get-net-subacct (category date) (let* ((from-vec (sbr/org-lookup-trans category date "$Subacct" "$From")) (to-vec (sbr/org-lookup-trans category date "$Subacct" "$To")) (amount-vec (sbr/org-lookup-trans category date "$Subacct" "$Amount")) (from-inbox-ind ) ; A (to-inbox-ind ) ; B (adds amount-vec[from-inbox-ind]) ; C (subs amount-vec[to-inbox-ind])) ; D (calc-eval (if (zerop (length subs)) adds (concat adds "-" subs))))) I need help filling in the pseudo code in lines A through D, namely: 1. how to get a list of all indices of elements in a vector that satisfy a predicate? 2. how to reference a vector by a list of indices? In this example the function should return the following values: (sbr/get-net-subacct "Bond" "150925") ==> 150 (sbr/get-net-subacct "Furnishings" "150925") ==> -75 (sbr/get-net-subacct "Baby Gifts" "150925") ==> -120 How do I implement the above pseudocode functions? Is there a simpler way to accomplish this task?