Array to substitute in Date

[jdukes42]

Hi All,

I have a wide data set containing drug names and start dates.

For each individual I want to transfer the start dates for each drug into a new variable. In cases where the drug is the same I want to use the earliest date as the new start date. See example below .

How can this be done using an array?

	RX_1	RX_2	RX_3	Start_1	Start_2	Start_3	New_dt1	New_dt2	New_dt3
1	1	2	2	01/20/05	01/29/05	1/30/05	01/20/05	01/29/05	1/29/05
2	1	2	3	01/20/05	01/20/05	1/21/05	01/20/05	01/20/05	1/21/05

Thanks,

Jonathan

[art297 · Accepted solution]

You don't really need arrays to do this, but you asked:

data want (drop=i j);

  set have;

  array old(*)Start_1-Start_3;

  array drug(*)RX_1-RX_3;

  array New_dt(3);

  format New_dt1-New_dt3 mmddyy8.;

  do i=1 to dim(old);

    New_dt(i)=old(i);

    do j=1 to i;

      if drug(i) eq drug(j) then do;

              New_dt(i)=min(New_dt(i),New_Dt(j));

              New_dt(j)=New_dt(i);

      end;

    end;

  end;

run;

[jdukes42]

Art297,

     Thank you for the swift reply and help.

Jonathan

[data_null__]

I thought WHICHN function might be useful.   But I probably don't understand the problem.

data have;

   input id RX_1-RX_3 (Start_1-Start_3)(:mmddyy.);

   array rx

rx_:;

   array s

start_:;

   array new[3];

   do i = 1 to dim(rx);

      new = s[whichN(rx,of rx

)];

      end;

   format start_: new: mmddyy.;

   drop i;

   cards;

1  1  2  2  01/20/05  01/29/05  1/30/05

2  1  2  3  01/20/05  01/20/05  1/21/05

;;;;

   run;

proc print;

   run;