@novinosrin  It seems I was happy too early. In my data I also have "freq" and"pct" columns, using your code, it turned out, for each item, the "freq" and "pct" columns picked the value in last row of each item. I tried to modify your code, but there is error. Could you please modify your code to fit my purpose? my data have is like the following data have; input item_id $ resp freq pct; datalines; pp1111 1 2 0.3 pp1111 2 5 0.5 pp1111 3 6 0.7 pp2222 1 3 0.4 pp2222 2 2 0.2 pp2222 3 4 0.5 pp2222 4 3 0.4 pp3333 1 6 0.8 pp3333 3 4 0.5 pp3333 4 10 0.7 pp4444 1 12 0.6 pp4444 2 9 0.5 pp5555 1 7 0.3 ; I want it to be like this data want; input item_id $ resp freq pct; datalines; pp1111 1 2 0.3 pp1111 2 5 0.5 pp1111 3 6 0.7 pp1111 pp2222 1 3 0.4 pp2222 2 2 0.2 pp2222 3 4 0.5 pp2222 4 3 0.4 pp3333 1 6 0.8 pp3333 pp3333 3 4 0.5 pp3333 4 10 0.7 pp4444 1 12 0.6 pp4444 2 9 0.5 pp4444 pp4444 pp5555 1 7 0.3 pp5555 pp5555 pp5555 ; thanks a bunch!   ... View more

@ballardw @Reeza @novinosrin  Thank you all fantastic SAS experts! You saved my day. A big thumb up to you all!   ... View more

@Kurt_Bremser @smantha @andreas_lds @mkeintz  Thanks for the suggestion of how to post effective questions! I am sorry for any inconveniences of all my previous posts. The picture below is the data I am having and the format I want. I hope the picture can be self-explaining. The data format I am having is like the A and B columns. Basically, each individual "item_id" is supposed to have four rows. If the rows of each individual "item_id" is less than four,  I want to make them to be four rows, like columns D and E. In column D, highlights in red is the rows that I want to insert. Thanks for the help!       ... View more

@novinosrin  Thanks much for the explanation and teaching! very much appreciate your help! ... View more

@ballardw  Thanks much for the help. SAS is running after incorporating the codes you suggested, but it turned out before SAS finish running the code, there is "disk out of space" message, so SAS stopped there and can't continue. How can I make the code more efficient and at the same time delete temporary SAS files generated in the "..user-->temp-->SAS temporary file"? thanks! ... View more

@Patrick  Thanks for the reply! I have 352 columns, I want to pick 4 columns, that is, combination of 4 from 352. The error message is "ERROR: Array subscript out of range at line 63 column 7", line 63 is  "k4=c(_n);" in the code.   ... View more

@novinosrin  Thank you for replying my post. Sorry for bothering you on the weekend. Of course I'll wait until you are available. Enjoy doing the weekend chores. Stay safe! ... View more

@novinosrin  a while ago, you help about pick a 2 people from a certain number of people. Now if I want to choose 4 people from a certain number of people, I am trying to modify the code you help, but there are error messages, could you help please. Below is the code for pick 4 people from a certain number of people.  Thanks much!   data comb1; set comb; array c col:; length cat $30 Pair $20; do _i=1 to dim(c)-1; do _j=_i+1 to dim(c); do _m=_j+1 to dim(c)+1; do _n=_m+1 to dim(c)+2; k1=c(_i); k2=c(_j); k3=c(_m); k4=c(_n); Pair=catx('_','Pair',_i,_j,_m,_n); if k1=k2=k3=k4=itemkey then cat="same resp and all correct"; else if k1=k2=k3=k4^=itemkey then cat="same resp and all wrong"; else if _i=itemkey or _j=itemkey or _m=itemkey or _n=itemkey then cat="different resp and one of them correct"; else cat="different resp and all wrong"; output; end; end; end; end; keep itempos itemkey cat pair; run; ... View more

@novinosrin  Many thanks! A big thumb to you! ... View more