topic Re: How to delete flagged variable with in a by group? in SAS Programming

How to delete flagged variable with in a by group?

Anna_nag — Wed, 11 Jun 2014 00:37:18 GMT

Hi All,

I have a programing question and would appreciate some suggestions.

I have a data set which has 6 variables: A1, A2, A3, A4, rank and flag.

A1,A2,A3,A4 is by group and within that by group I want to delete flag=1 but its not that simple, I want to delete only those flags which leaves me with consecutive rank variable.

For eg:

A1 A2 A3 A4 Rank Flag

1 1 1 1 1 0

1 1 1 1 2 1 -by Group1

1 1 1 1 3 0

1 1 1 1 4 1

1 1 1 2 1 1

1 1 1 2 2 1

1 1 1 2 3 0

1 1 1 2 4 1 -> by Group2

1 1 1 2 5 1

1 1 1 2 6 0

1 1 1 2 7 1

Result I want:

A1 A2 A3 A4 Rank Flag

1 1 1 1 1 0

1 1 1 1 2 1 -> by Group1

1 1 1 1 3 0

1 1 1 2 3 0

1 1 1 2 4 1 -> by Group2

1 1 1 2 5 1

1 1 1 2 6 0

Here important thing is not to break the sequence of rank
variable. I cant have rank 3,6 only in group 2

Re: How to delete flagged variable with in a by group?

Haikuo — Wed, 11 Jun 2014 02:12:42 GMT

Typically you would need more than one pass, here is an example using 2XDOW:

data have;

input A1 A2 A3 A4 Rank Flag;

cards;

1 1 1 1 1 0

1 1 1 1 2 1

1 1 1 1 3 0

1 1 1 1 4 1

1 1 1 2 1 1

1 1 1 2 2 1

1 1 1 2 3 0

1 1 1 2 4 1

1 1 1 2 5 1

1 1 1 2 6 0

1 1 1 2 7 1

;;;;

run;

data want;

do until (last.flag);

set have;

by a4 flag notsorted;

if (first.a4 or last.a4) and flag then

_d=1;

end;

do until (last.flag);

set have;

by a4 flag notsorted;

if missing(_d) then

output;

end;

run;

Regards,

Haikuo

Re: How to delete flagged variable with in a by group?

Haikuo — Wed, 11 Jun 2014 12:17:33 GMT

@anna_nag,

DOW loop is an classic data step implementation that is both powerful and convenient to use. Recently the Hash() and Proc SQL have stolen some thunders from DOW, but as you can see, it still shines here. However, if you have never used or heard of it, it would be very hard for me to explain it in a format of short post. The concept of DOW touches the heart of data step. Here are some references that you may want to take a look:

http://support.sas.com/resources/papers/proceedings12/156-2012.pdf

http://www.pharmasug.org/proceedings/2012/AD/PharmaSUG-2012-AD29.pdf

Another key of my code is to use option: "notsorted". This is to take your current data structure as is, then group it using "by variables". Please also do a search to learn more.

Regards,

Haikuo

Re: How to delete flagged variable with in a by group?

Ksharp — Wed, 11 Jun 2014 13:20:53 GMT

data have;
input A1   A2  A3  A4  Rank  Flag ;
cards;
1      1      1     1     1            0
1      1      1     1     2            1         
1      1      1     1     3            0
1      1      1     1     4            1
1      1      1     2     1            1
1      1      1     2     2            1
1      1      1     2     3            0
1      1      1     2     4            1       
1      1      1     2     5            1
1      1      1     2     6            0
1      1      1     2     7            1
;
run;
data have;
 set have;
 by a1 a2 a3 a4;
 if first.a4 or flag ne lag(flag) then n+1;
run;
proc sql;
 create table want as
  select * from have 
   except
  select * from have
   group by a1,a2,a3,a4 
    having (n eq max(n) and flag=1) or (n eq min(n) and flag=1);
quit;

Xia Keshan

Re: How to delete flagged variable with in a by group?

Anna_nag — Wed, 11 Jun 2014 15:40:36 GMT

Thanks..it works!!