topic Re: Clustering in SAS Programming

Clustering

Himanshu007 — Fri, 02 Jun 2017 11:14:33 GMT

My data looks like this:-

Latitude Longitude

26.89155 75.82533
26.89156 75.82563
26.896437 75.827229

26.89111 75.819003
26.899911 75.813517
26.89716 75.813694
26.897943 75.813052
26.89255 75.813286

I have to make clusters of areas with a radius of 250metres.

Re: Clustering

PeterClemmensen — Fri, 02 Jun 2017 12:50:31 GMT

So what would your output data look like?

Re: Clustering

Ksharp — Fri, 02 Jun 2017 13:10:07 GMT

Check GEODISTANCE() to get the distance between two points and use SQL to get what you want.

Re: Clustering

ballardw — Fri, 02 Jun 2017 14:24:58 GMT

@Ksharp wrote:

Check GEODISTANCE() to get the distance between two points and use SQL to get what you want.

Maybe GEODIST ?

Re: Clustering

Ksharp — Fri, 02 Jun 2017 15:15:00 GMT

Yeah. Too many function name in my mind.

data have;
input Latitude            Longitude;
id+1;
cards;
26.89155         75.82533
26.89156         75.82563
26.896437       75.827229
26.89111          75.819003
26.899911       75.813517
26.89716         75.813694
26.897943       75.813052
26.89255         75.813286
;
run;

proc sql;
select a.*,b.id as _id,geodist(a.Latitude,a.Longitude,b.Latitude,b.Longitude,'M') as dis
 from have as a,have as b
  where a.id ne b.id
  order by id,_id;
quit;

Re: Clustering

Himanshu007 — Sat, 03 Jun 2017 07:22:59 GMT

Firstly Thanks a lot for your solution,

But the problem i m getting is that this solution makes the same input(lat,long) appear a number of times.

What I want is that points that form a cluster be grouped as cluster_1 and so on.

I hope you understand my problem.

Re: Clustering

Ksharp — Sat, 03 Jun 2017 10:45:11 GMT

OK. Here is .

data have;
input Latitude            Longitude;
id+1;
cards;
26.89155         75.82533
26.89156         75.82563
26.896437       75.827229
26.89111          75.819003
26.899911       75.813517
26.89716         75.813694
26.897943       75.813052
26.89255         75.813286
;
run;

proc sql;
create table temp as
select a.*,b.id as _id,
geodist(a.Latitude,a.Longitude,b.Latitude,b.Longitude,'k')*1000 as dis
 from have as a,have as b
  where a.id ne b.id and calculated dis < 250
  order by id,_id;
quit;
data have;
 set temp;
 call sortn(id,_id);
 keep id _id;
 rename id=from _id=to;
run;






/********Start to cluster***********/
data full;
  set have end=last;
  if _n_ eq 1 then do;
   declare hash h();
    h.definekey('node');
     h.definedata('node');
     h.definedone();
  end;
  output;
  node=from; h.replace();
  from=to; to=node;
  output;
  node=from; h.replace();
  if last then h.output(dataset:'node');
  drop node;
run;


data want(keep=node household);
declare hash ha(ordered:'a');
declare hiter hi('ha');
ha.definekey('count');
ha.definedata('last');
ha.definedone();
declare hash _ha(hashexp: 20);
_ha.definekey('key');
_ha.definedone();

if 0 then set full;
declare hash from_to(dataset:'full(where=(from is not missing and to is not missing))',hashexp:20,multidata:'y');
 from_to.definekey('from');
 from_to.definedata('to');
 from_to.definedone();

if 0 then set node;
declare hash no(dataset:'node');
declare hiter hi_no('no');
 no.definekey('node');
 no.definedata('node');
 no.definedone();
 

do while(hi_no.next()=0);
 household+1; output;
 count=1;
 key=node;_ha.add();
 last=node;ha.add();
 rc=hi.first();
 do while(rc=0);
   from=last;rx=from_to.find();
   do while(rx=0);
     key=to;ry=_ha.check();
      if ry ne 0 then do;
       node=to;output;rr=no.remove(key:node);
       key=to;_ha.add();
       count+1;
       last=to;ha.add();
      end;
      rx=from_to.find_next();
   end;
   rc=hi.next();
end;
ha.clear();_ha.clear();
end;
stop;
run;