Fill NA with next value

[PatrykSAS]

I'd like to fill missing values with the previous one like in below example:

Date	Value
2021-08-01	10
2021-08-02

Result:

Date	Value
2021-08-01	10
2021-08-02	10

How can I do it in a fast way?

[PaigeMiller]

Please clarify your request.

In the title, you say you want the NEXT value, but in your text you say you want the PREVIOUS value. These are not the same. Which is it?

[maguiremq]

You can do something like this, but I'm also quite certain that there are additional complexities that you didn't capture in your example. Nonetheless, try this:

data have;
infile datalines missover;
input date :yymmdd10. value;
format date yymmdd10.;
datalines;
2021/08/01 10
2021/08/02 .
;

data want;
	set have;
		lag_val = lag(value);
		if missing(value) then value = lag_val;
	drop lag_val;
run;

date value 
2021-08-01 10 
2021-08-02 10 

You can remove the

drop lag_val;

if you want to see what's going on.

[PaigeMiller]

... but I'm also quite certain that there are additional complexities that you didn't capture in your example ...

I'm glad you pointed that out @maguiremq , I was thinking the same thing. 

[maguiremq]

Things are never as simple as they seem, right?