Counting the number of specific rows using Hash

[jimmychoi]

Hi, I have two datasets

data deal;
  compressed_a = 'WYETH'; compressed_b = 'FORTDODGEANIMALHEALTH'; year = 1945;output;
  compressed_a = 'ELILILLYANDCOMPANY'; compressed_b = 'HYBRITECHINCORPORATED'; year = 1985;output;
  compressed_a = 'GENENTECH'; compressed_b = 'ABBOTTLABORATORIES'; year = 1990;output;
run;

data patent;
  firmname = 'GENENTECH'; pnyear = 1985; IPC = 'B05C'; output;
  firmname = 'ELILILLYANDCOMPANY'; pnyear = 1983; IPC = 'A01N'; output;
run;

table deal has the M&A data of two firms, including firm names (compressed_a, compressed_b) and the year of the deal was conducted.

table patent has the list of ipc codes of a firm has acquired.

my main question is this: How many number of patents does a company has, at a focal year (deal year).

expected output(ipc_a indicating number of patents, accumulative)

compressed_a	compressed_d	year	ipc_a	ipc_b
WYETH	FORTDODGEANIMALHEALTH	1945	0	0
ELILILLYANDCOMPANY	HYBRITECHINCORPORATED	1985	1	0
GENENTECH	ABBOTTLABORATORIES	1990	1	0

thus i have constructed a code as below:

data size_merge5;
  if _n_=1 then do;
	if 0 then set patent;
	dcl hash H (dataset:'patent',multidata:'y') ;
	h.definekey  ("firmname") ;
	h.definedata ("pnyear","ipc") ;
	h.definedone () ;
  end;

  set deal;  

  IPC_A=0;
  do rc=h.find(key:'compressed_a') by 0 while(rc=0);		
	if pnyear < year then IPC_A =sum(IPC_A,1);	
	rc=h.find_next();
  end;

  IPC_B=0;
  do rc=h.find(key:'compressed_b') by 0 while(rc=0);		
	if pnyear < year then IPC_B =sum(IPC_B,1);	
	rc=h.find_next();
  end;

run;

but unfortunately this code gives me all zeros for ipc_a and ipc_b.

cannot find what's wrong. please help.

[RW9]

Why not just merge on based on compressed_a=firmname?  Thats all you seem to want from that snippet?  If it needs to match both, then merge twice (same datastep) and just rename the variable?

/* Note both assumes sorted */
data want;
  merge deal
             patent (rename=(firmname=compressed_a ipc=ipc1));
  by compressed_a;
run;
data want;
  merge want
             patent (rename=(firmname=compress_b ipc=ipc2));
  by compressed_b;
run;

[jimmychoi]

i am trying to count the accumulative count of IPC codes

[mkeintz · Accepted solution]

First, thank you for provide a complete program, with sample data. 

There are two problems - one having to do with hash object method use, and the other with character variable length:

1. Character variable length.  Because the first assignment of compressed_a='WYETH', that variable was assigned a length of $5, thereby truncating values of compressed_a in other observations.  Same with firmname (length=$9) in data set patents.  So assign length by means of a LENGTH statement in your sample.
   
   But probably your actual data does not suffer from this issue.  In this case, you may have inadvertently added to the problem by making the sample data sets via assignment statements instead of INPUT.
2. hash object usage.  By specifying    h.find(key:'compressed_a') you were looking for a data itemtime with a key VALUE of 'compressed_a'.  You should specify   h.find(key:compressed_a), which takes the value in variable compressed_a.

data deal;
  length compressed_a  compressed_b $24;
  compressed_a = 'WYETH';              compressed_b = 'FORTDODGEANIMALHEALTH'; year = 1945;output;
  compressed_a = 'ELILILLYANDCOMPANY'; compressed_b = 'HYBRITECHINCORPORATED'; year = 1985;output;
  compressed_a = 'GENENTECH';          compressed_b = 'ABBOTTLABORATORIES';    year = 1990;output;
run;
data patent;
  length firmname $24;
  firmname = 'GENENTECH';          pnyear = 1985; IPC = 'B05C'; output;
  firmname = 'ELILILLYANDCOMPANY'; pnyear = 1983; IPC = 'A01N'; output;
run;

data size_merge5;
  if _n_=1 then do;
	if 0 then set patent;
	dcl hash H (dataset:'patent',multidata:'y') ;
	h.definekey  ("firmname") ;
	h.definedata ("pnyear","ipc") ;
	h.definedone () ;
  end;

  set deal;  

  IPC_A=0;
  do rc=h.find(key:compressed_a) by 0 while(rc=0);		
	if pnyear < year then IPC_A =sum(IPC_A,1);	
	rc=h.find_next();
  end;

  IPC_B=0;
  do rc=h.find(key:compressed_b) by 0 while(rc=0);		
	if pnyear < year then IPC_B =sum(IPC_B,1);	
	rc=h.find_next();
  end;

run;

[jimmychoi]

mkeintz, my savior!
you're right i wasn't suffering from the issue #1 with my actual data but was suffering because of issue #2!!! just by removing single quotes, it works now. THANKS SO MUCH