Return column with most recent date, array error

[MB_Analyst]

I was using the answer to this question, in order to return the column name with the latest date. My data is in this format:

DATA have;
    INPUT id away :DATE9. home :DATE9. travel :DATE9.;
    FORMAT away home travel DATE9.;
DATALINES;
1 . . 01JAN2020
2 03JAN2020 . 03FEB2020
3 04FEB2020 01JAN2020 12FEB2020
;

Using the solution to the other question I have this code (I didn't want to include the ID in the array, so I had to drop it, then bring it back in):

DATA want;
    SET have(drop=id);
    ARRAY dates[*] _numeric_;
    SET have;
    latest = max(of dates[*]);
    maxv = vname(dates[whichn(latest, of dates(*))]);
RUN;

Everything runs fun if I leave out the line maxv = vname..., but leaving it in gives me an error:

ERROR: Array subscript out of range at line 1068 column 18.

What is causing this error to come up in the last line of the code?

[Ksharp]

You have TWO "SET have;" , drop the last one .

[MB_Analyst]

I initially did this so I could use _NUMERIC_ to define the array, without using the ID variable. I still need the ID variable - is there a better way to achieve this? The data set I'm using has many variables for the array, and are likely to change. Should I force the ID as a character instead?

[novinosrin · Accepted solution]

HI @MB_Analyst  Your code successfully ran when i tested. Here is the log

1716  DATA have;
1717      INPUT id away :DATE9. home :DATE9. travel :DATE9.;
1718      FORMAT away home travel DATE9.;
1719  DATALINES;

NOTE: The data set WORK.HAVE has 3 observations and 4 variables.
NOTE: DATA statement used (Total process time):
      real time           0.01 seconds
      cpu time            0.01 seconds


1723  ;
1724
1725  DATA want;
1726      SET have(drop=id);
1727      ARRAY dates[*] _numeric_;
1728      SET have;
1729      latest = max(of dates[*]);
1730      maxv = vname(dates[whichn(latest, of dates(*))]);
1731  RUN;

NOTE: There were 3 observations read from the data set WORK.HAVE.
NOTE: There were 3 observations read from the data set WORK.HAVE.
NOTE: The data set WORK.WANT has 3 observations and 6 variables.
NOTE: DATA statement used (Total process time):
      real time           0.00 seconds
      cpu time            0.00 seconds

Btw, this makes me wonder whether your sample data is a good representative of your real?

Also does any of your records have all missings that eventually makes the MAX value also as missing? Please verify

[MB_Analyst]

It was a missing value in the MAX. I was able to avoid the error with:
If NOT MISSING(latest) THEN DO;
maxv = vname(dates[whichn(latest, of dates(*))]);
END;

[novinosrin]

Good and I am glad. You are not alone. I have had that issue many times. The thumb rule is always to be very cognizant of missing values and its propagation.