topic HASH LEFT join : how to use min or max in the key and keep the original value of the variable in SAS Programming

HASH LEFT join : how to use min or max in the key and keep the original value of the variable

bebess — Thu, 08 Nov 2018 14:27:10 GMT

/* i want to use min and max in my key to join through HASH like in SQL :

min(t1.keyvar,5) = t2.keyvar)

/* i have 45 to 49 in my left table and i have 50 in the table i want to join */

/* i am using the following code in my hash left join code for that , but when i do that the "varkey" column is not the original one ( not the orignal value) in my result table , the max replace the original value (here 50 ) */

data want (drop=rc);

/*iterate left data set*/

set have ;

/*declare variables from hash set*/

length b rc 8 ;

/*declare hash*/

if _n_=1 then

do;

declare hash hhh(dataset: "tableb (keep=keyvar b)", multidata:'y');

hhh.DefineKey('keyvar');

hhh.DefineData(ALL:'YES');

hhh.DefineDone();

end;

do until(Lastobs);

set have end=Lastobs;

call missing(b);

rc = hhh.find(key:max(50,min(keyvar,55)));

if rc ne 0 then

do;

var=.

output;

end;

do while (rc=0);

var =a*b;

output;

rc = hhh.find_next();

end;

run;

Re: HASH LEFT join : how to use min or max in the key and keep the original value of the variable

PeterClemmensen — Thu, 08 Nov 2018 14:31:03 GMT

Can you post some example data and what you want the desired result to look like from that data?

Re: HASH LEFT join : how to use min or max in the key and keep the original value of the variable

PeterClemmensen — Thu, 08 Nov 2018 14:37:23 GMT

Also, you are missing a semicolon setting var to missing. And proper indentation doesn't hurt either 🙂

data want (drop=rc);
   set have;
   length b rc 8;

   if _n_=1 then do;
      declare hash hhh(dataset: "tableb (keep=keyvar b)", multidata:'y');
      hhh.DefineKey('keyvar');
      hhh.DefineData(ALL:'YES');
      hhh.DefineDone();
   end;

   do until(Lastobs);
      set have end=Lastobs;
      call missing(b);
      rc = hhh.find(key:max(50,min(keyvar,55)));

      if rc ne 0 then do;
         var=.;
         output;
      end;

      do while (rc=0);
         var =a*b;
         output;
         rc = hhh.find_next();
      end;
   end;
run;

Re: HASH LEFT join : how to use min or max in the key and keep the original value of the variable

bebess — Thu, 08 Nov 2018 16:07:42 GMT

/* i want to replicate the followinf sql code in hash * /

proc sql;

create table want as

select a.*,b.coef

from bigtable as a

left join smalltable (keep=AGE coef) as b

on max(50,min(a.AGE,55))=b.AGE

;

quit;

Re: HASH LEFT join : how to use min or max in the key and keep the original value of the variable

novinosrin — Thu, 08 Nov 2018 16:37:00 GMT

Hi @bebess Can you post sample(example data) that @PeterClemmensen requested to work with

I don't know about others. Pardon me, I am too lazy

Re: HASH LEFT join : how to use min or max in the key and keep the original value of the variable

bebess — Thu, 08 Nov 2018 16:54:59 GMT

DATA smalltable;

INPUT age coef ;

DATALINES ;

50 1

51 2

52 3

53 4

54 5

55 6

;

RUN;

DATA bigtable;

INPUT age ;

DATALINES ;

41 1

41 2

42 3

43 4

44 5

45 6

;

RUN;

/* sql : result i want to have */

proc sql;

create table want as

select a.*,b.coef

from bigtable as a

left join smalltable (keep=AGE coef) as b

on max(50,min(a.AGE,55))=b.AGE

;

quit;

/* Test: how to do in hash , I HAVE age=50 in the result table whereas i expect to have 41 to 45*/

data want (drop=rc);

set bigtable;

length coef rc 8;

if _n_=1 then do;

declare hash hhh(dataset: "smalltable (keep=AGE coef)", multidata:'y');

hhh.DefineKey('AGE');

hhh.DefineData(ALL:'YES');

hhh.DefineDone();

end;

do until(Lastobs);

set bigtable end=Lastobs;

call missing(coef);

rc = hhh.find(key:max(50,min(AGE,55)));

if rc ne 0 then do;

var_calculated=.;

output;

end;

do while (rc=0);

var_calculated =AGE*coef;

output;

rc = hhh.find_next();

end;

run;

Re: HASH LEFT join : how to use min or max in the key and keep the original value of the variable

bebess — Thu, 08 Nov 2018 17:05:07 GMT

/* i think the reason is because i put ALL:YES in definedata , if i remove AGE i have the table that i expect , is there a way/ option to put all but only remove a list of variable in the definedata() ? */

/* thank everyone for your help i appreciate 🙂 */

data want (drop=rc);

set bigtable;

length coef rc 8;

if _n_=1 then do;

declare hash hhh(dataset: "smalltable (keep=AGE coef)", multidata:'y');

hhh.DefineKey('AGE');

hhh.DefineData('coef');

hhh.DefineDone();

end;

do until(Lastobs);

set bigtable end=Lastobs;

call missing(coef);

rc = hhh.find(key:max(50,min(AGE,55)));

if rc ne 0 then do;

var_calculated=.;

output;

end;

do while (rc=0);

var_calculated =AGE*coef;

output;

rc = hhh.find_next();

end;

run;

Re: HASH LEFT join : how to use min or max in the key and keep the original value of the variable

FreelanceReinh — Thu, 08 Nov 2018 17:17:06 GMT

@bebess wrote:
I HAVE age=50 in the result table whereas i expect to have 41 to 45

Hi @bebess,

This is because you overwrite the age values with those from SMALLTABLE. To avoid this you can restrict the data items of the hash object to 'coef':

data want(drop=rc);
length coef 8;

if _n_=1 then do;
  declare hash hhh(dataset:'smalltable(keep=age coef)', multidata:'y');
  hhh.definekey('age');
  hhh.definedata('coef');
  hhh.definedone();
end;

do until(lastobs);
  set bigtable end=lastobs;
  call missing(coef);
  rc = hhh.find(key:max(50,min(age,55)));

  if rc ne 0 then output;

  do while(rc=0);
    output;
    rc = hhh.find_next();
  end;
end;
run;

Re: HASH LEFT join : how to use min or max in the key and keep the original value of the variable

novinosrin — Thu, 08 Nov 2018 17:13:24 GMT

data want2 (drop=rc);

set bigtable;

length coef rc 8;

if _n_=1 then do;

declare hash hhh(dataset: "smalltable (keep=AGE coef)", multidata:'y');

hhh.DefineKey('AGE');

hhh.DefineData('coef');

 

hhh.DefineDone();

end;

do until(Lastobs);

set bigtable end=Lastobs;

call missing(coef);

rc = hhh.find(key:max(50,min(AGE,55)));

if rc ne 0 then do;

var_calculated=.;

output;

end;

do while (rc=0);

 

var_calculated =AGE*coef;

output;

 

rc = hhh.find_next();

end;

end;

run;

Re: HASH LEFT join : how to use min or max in the key and keep the original value of the variable

FreelanceReinh — Thu, 08 Nov 2018 17:28:40 GMT

What about renaming AGE from smalltable?

data want(drop=rc _age);
length _age coef 8;

if _n_=1 then do;
  declare hash hhh(dataset:'smalltable(keep=age coef rename=(age=_age))', multidata:'y');
  hhh.definekey('_age');
  hhh.definedata(all:'y');
  hhh.definedone();
end;

do until(lastobs);
  set bigtable end=lastobs;
  call missing(_age,coef);
  rc = hhh.find(key:max(50,min(age,55)));

  if rc ne 0 then output;

  else do while(rc=0);
    output;
    rc = hhh.find_next();
  end;
end;
run;

Edit: Inserted "else" for a (marginal) performance improvement.

Re: HASH LEFT join : how to use min or max in the key and keep the original value of the variable

FreelanceReinh — Thu, 08 Nov 2018 17:46:44 GMT

@bebess wrote:

rc = hhh.find(key:max(50,min(AGE,55)));

By the way, missing values of AGE in bigtable would be matched with observations from smalltable with AGE=55. I hope this is what you intended (or there are no obs. with missing AGE in bigtable).