Date:         Tue, 20 May 2003 14:45:11 -0700
Reply-To:     Ramesh Makkena <makkena@XOMA.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
Comments:     To: "Huang, Ya" <yhuang@AMYLIN.COM>
From:         Ramesh Makkena <makkena@XOMA.COM>
Subject:      Re: Best way to test missing value?
Comments: To: SAS-L@LISTSERV.VT.EDU
Content-Type: text/plain; charset="iso-8859-1"

Ya,

I always use missing function instead of . If you use missing(a) then you would be fine.

1     data _null_;
2     a=.;
3     b=(a=.);
4     put a= b=;
5     a=.k;
6     b=(a=.);
7     put a= b=;
8     a=.k;
9     b=(nmiss(a)=1);
10    put a= b=;
11    a=.k;
12    b=(missing(a));
13    put a= b=;
14    run;

A=. B=1
A=K B=0
A=K B=1
A=K B=1
NOTE: DATA statement used:
      real time           0.51 seconds
      cpu time            0.03 seconds

Ramesh Makkena


-----Original Message-----
From: Huang, Ya [mailto:yhuang@AMYLIN.COM]
Sent: Tuesday, May 20, 2003 9:59 AM
To: SAS-L@LISTSERV.VT.EDU
Subject: Best way to test missing value?


Hi there,

I usually use "if a=. then ..." to test if a variable's value is
missing, but was burned today, because one of the var has many different
missing values, as a result "if a=. then .." failed to detect a=.k.
I then use "if nmiss(a)=1 then ..", which works fine. I just wonder
how you guys handle this kind of situation.

61   data _null_;
62   a=.;
63   b=(a=.);
64   put a= b=;
65   a=.k;
66   b=(a=.);
67   put a= b=;
68   a=.k;
69   b=(nmiss(a)=1);
70   put a= b=;
71   a=.k;
72   b=(a = missing);
73   put a= b=;
74   run;

NOTE: Variable missing is uninitialized.
a=. b=1
a=K b=0
a=K b=1
a=K b=0

I vaguely remember seeing someone use 'missing' as a key word,
but the above log shows it dose not work.

Thanks

Ya