# Is it possible to create a set from a parameter? **URL:** \ **Category:** Support\ **Created:** [July 16, 2026, 12:06pm UTC](https://discuss.ampl.com/t/is-it-possible-to-create-a-set-from-a-parameter/2280 "2026-07-16T12:06:15Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Lothar\_Lower](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.ampl.com/lothar_lower/32/855_2.png) [@Lothar\_Lower](https://discuss.ampl.com/u/Lothar_Lower)\ **Post date:** [July 16, 2026, 12:06pm UTC](https://discuss.ampl.com/t/is-it-possible-to-create-a-set-from-a-parameter/2280/1 "2026-07-16T12:06:15Z")
I am reading parameter from an excel-file using amplxl.dll. Partly, the parameter data (columns in excel) contain empty data. set MPC\_BRA\_ID default {}; param bra\_type{MPC\_BRA\_ID} symbolic default ‘’; param bra\_tap\_pos{MPC\_BRA\_ID}; # no default here so far table tmp\_table IN “amplxl” (filename\_GRID) “mpc\_bra”: MPC\_BRA\_ID ← [mpc\_bra\_id], bra\_type, bra\_tap\_pos; read table tmp\_table; As a result, let’s assume five branches, MPC\_BRA\_ID is a set containing five values. Also bra\_type contains five values since every branch has a type information like “line” or “transformer”. Having a look at bra\_tap\_position, some indices are missing because a value is only defined for a few transformer within the excel file. A lot of cells are simply empty. e.g. display bra\_tap\_pos; bra\_tap\_pos [\*] = 3 0 5 2 ; I want to create a new set dealing with the branches, which have a tap-position information. The result shall be: new\_set = {3, 5}; Unfortunatelly, “0” is a valid information too. Thus, replacing the empty cell by “0” would mean that the transformer has tap position data. Evaluating the command set new\_set = {i in MPC\_BRA\_ID: bra\_tap\_pos[i]}; contains only the indices which are not “0”. Is there any possibility to create such a set, without using a default value outside a realistic range (param bra\_tap\_pos{MPC\_BRA\_ID} default -9999)? Best regards, Lothar ---
**Author:** ![4er](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.ampl.com/4er/32/530_2.png) [@4er](https://discuss.ampl.com/u/4er)\ **Post date:** [July 17, 2026, 7:20pm UTC](https://discuss.ampl.com/t/is-it-possible-to-create-a-set-from-a-parameter/2280/2 "2026-07-17T19:20:46Z")
There’s no easy way to define the set of “all bra\_tap\_pos[i] that have received a value so far.” Using `default -9999` is a clean approach, however. [test.txt](https://discuss.ampl.com/uploads/short-url/1L4VGWiokSDI323qRPpIFApGyF.txt) (446 Bytes) [test.xlsx](https://discuss.ampl.com/uploads/short-url/hTyVTdhaikCnC3d7KU8ODdCtOei.xlsx) (8.3 KB) ---
**Author:** ![marcos](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.ampl.com/marcos/32/154_2.png) [@marcos](https://discuss.ampl.com/u/marcos)\ **Post date:** [July 17, 2026, 10:41pm UTC](https://discuss.ampl.com/t/is-it-possible-to-create-a-set-from-a-parameter/2280/3 "2026-07-17T22:41:31Z")
Hi @Lothar_Lower , Just a remark, it could be more convenient to use `amplpy` to interact with tables or spreadsheets in python rather than read/update them in `ampl`. Data manipulation is usually easier in python ---
**Author:** ![Lothar\_Lower](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.ampl.com/lothar_lower/32/855_2.png) [@Lothar\_Lower](https://discuss.ampl.com/u/Lothar_Lower)\ **Post date:** [July 23, 2026, 9:50am UTC](https://discuss.ampl.com/t/is-it-possible-to-create-a-set-from-a-parameter/2280/4 "2026-07-23T09:50:41Z")
Hi Robert & Marcos, Thank’s for the reply. So I will read the data using a default value of -9999 and create the set based on another set excluding all members which have a bra\_tap\_pos of this value. Best regards, Lothar