Take last value for missing value(more than 1 missing value)

[gahlot1999]

Hi Community,

In my dataset, there are multiple missing values. I want those missing values to be filled with last value. If two or more than two missing value then all consecutive missing values should take last value which existed.

For ex.

Source Data:

Source	Output
1	1
1	1
1	1
2	2
2	2
	2
	2
	2
4	4

[Tom]

That is want is called Last Observation Carried Forward (LOCF).

For that data a simple retained variable will work.  Note that the retained variable needs to be a NEW variable (not one already in the source dataset) otherwise the retained value is overwritten when the next observation is read.

data have;
  input Source Output;
cards;
1 1
1 1
1 1
2 2
2 2
. 2
. 2
. 2
4 4
;

data want;
  set have;
  want = coalesce(source,want);
  retain want;
run;

Result

Obs    Source    Output    want

 1        1         1        1
 2        1         1        1
 3        1         1        1
 4        2         2        2
 5        2         2        2
 6        .         2        2
 7        .         2        2
 8        .         2        2
 9        4         4        4