filling blanks with duplicate keys

[brophymj]

Is there a simple way of duplicating the key until it reaches the next values so

key

5564

blank

blank

blank

5566

becomes

5564

5564

5564

5566

5566

thanks

I have attached my dataset

[RW9]

You can use retain:

data have;

  key=5564; output;

  key=.; output;

  key=.; output;

  key=.; output;

  key=5566; output;

run;

data want (drop=key rename=(new_key=key));

  set have;

  retain new_key;

  if key ne . then new_key=key;

run;

Lag would also work if its a new variable.