sas hash table with multiple key value pairs - sas

Question

I have a lookup table which looks like this (Name: LOOKUP_TABLE):
Obs Member_id plan_id Plan_desc group_id Group_name
1 164-234 XYZ HMO_Salaried G123 Umbrellas, Inc.
2 297-123 ABC PPO_Hourly G123 Umbrellas, Inc.
3 344-123 JKL HMO_Executive G456 Toy Company
4 395-123 XYZ HMO_Salaried G123 Umbrellas, Inc.
5 495-987 ABC PPO_Hourly G456 Toy Company
6 562-987 ABC PPO_Hourly G123 Umbrellas, Inc.
7 697-123 XYZ HMO_Salaried G456 Toy Company
I have another table with the following data (Name: MAIN_TABLE):
Obs Member_id zip income svc_dt dx plan_id group_id Obs old_id new_id
1 164-234 04021 $45,000 2005/01/01 250 XYZ G123 1 164-234 N164-234
2 297-123 22003-1234 $56,999 2005/02/03 4952 ABC G123 2 297-123 N297-123
3 344-123 45459-0306 $72,999 2005/03/15 78910 JKL G456 3 344-123 C344-123
4 395-123 03755 $75,000 2005/04/14 250 XYZ G123 4 N164-234 M164-234
5 495-987 94305 $96,000 2005/08/19 12345 ABC G456 5 N297-123 B297-123
6 562-987 78277-8310 $32,999 2005/09/13 250 ABC G123 6 M164-234 P164-234
7 697-123 88044-3760 $47,999 2005/11/01 4952 XYZ G456 7 P164-234 A164-234
My SAS data step is as follows:
data MAIN_TABLE_1.
set MAIN_TABLE;
declare hash pd_lookup(dataset:"&LOOKUP_TABLE.");
rc_pd_definekey = pd_lookup.definekey
(
'plan_id',
'group_id'
);
rc_pd_definedata = pd_lookup.definedata
(
'Plan_desc',
'Group_name'
);
rc_pd_definedone = pd_lookup.definedone();
call missing (
Plan_desc,
Group_name
);
put "rc_pd_definekey is " rc_pd_definekey;
put "rc_pd_definedata is " rc_pd_definedata;
put "rc_pd_definedone is " rc_pd_definedone;
drop rc_pd_definekey rc_pd_definedata rc_pd_definedone;
rc_pd_lookup = pd_lookup.find();
run
My question is to understand whats happening behind the scenes in this lookup, mainly with regards to the key value pairs being generated.
i.e., are there individual key value pairs being generated.
As in , the example of key value pairs will be
: "plan_id" -> "Plan_desc"
: "plan_id" -> "Group_name"
: "group_id" -> "Plan_desc"
: "group_id" -> "Group_name"
Or is it that the keys are concatenated together and so are the values, and then we make pairs.
As in, something like this
:"plan_id"+"group_id" -> "Plan_desc" + "Group_name"
I ask this question as I have to convert the same code logic into R, and if I misunderstand, then the whole R code will be wrong

Answer 1

Each combination of plan_id and group_id is used to retrieve a unique entry from the hash table containing values of both plan_desc and group_name.
However, currently there are duplicate rows with the same combination of these ids in the lookup table, which may cause errors or unexpected behaviour - e.g. obs 1 and 4. You should create a deduplicated copy of the lookup table and use that to declare the hash object.