good day all,
here is my data set
Obs | Date | rownum |
---|---|---|
1 | 01APR2021 | 1 |
2 | . | 2 |
3 | 02APR2021 | 3 |
4 | 05APR2021 | 4 |
5 | 06APR2021 | 5 |
6 | 07APR2021 | 6 |
7 | . | 7 |
8 | 08APR2021 | 8 |
9 | 09APR2021 | 9 |
10 | 12APR2021 | 10 |
11 | . | 11 |
12 | 13APR2021 | 12 |
13 | 14APR2021 | 13 |
14 | 15APR2021 | 14 |
15 | 16APR2021 | 15 |
16 | 19APR2021 | 16 |
17 | 20APR2021 | 17 |
18 | 21APR2021 | 18 |
19 | 22APR2021 | 19 |
20 | 23APR2021 | 20 |
21 | 26APR2021 | 21 |
22 | 27APR2021 | 22 |
23 | 28APR2021 | 23 |
24 | 29APR2021 | 24 |
25 | 30APR2021 | 25 |
for the missing value, i want to write a program for auto look up the upper value.
for the example Obs 2 will equal 01APR2021. i know a function called retain would do . But can i use if then for my question? if date is missing , then date = date (current rownum-1). if it is possible, i can be more creative in my future program. thanks you
Regards,
Harry
Here is a way to use an IF test, via the IFN function:
data want;
set have;
date=ifn(date=.,lag(date),date);
run;
But this only replaces all missing date values when there are never two consecutive missing date values.
A more general solution:
data want (drop=_:);
set have (rename=(date=_check));
if _check ^=. then set have point=_n_;
run;
This relies on the fact that variables read via a SET statement are automatically retained - until another SET reads in the same variable, which usually happens with every incoming obs. But the conditional set statement above (if _check^=. then set have point=_n_) only reads non-missing values for DATE and automatically retains that value. And unlike the first example, this would propagate non-missing DATE values over multiple consecutive observations with missing values for _CHECK.
Here is a way to use an IF test, via the IFN function:
data want;
set have;
date=ifn(date=.,lag(date),date);
run;
But this only replaces all missing date values when there are never two consecutive missing date values.
A more general solution:
data want (drop=_:);
set have (rename=(date=_check));
if _check ^=. then set have point=_n_;
run;
This relies on the fact that variables read via a SET statement are automatically retained - until another SET reads in the same variable, which usually happens with every incoming obs. But the conditional set statement above (if _check^=. then set have point=_n_) only reads non-missing values for DATE and automatically retains that value. And unlike the first example, this would propagate non-missing DATE values over multiple consecutive observations with missing values for _CHECK.
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