topic selecting only certain observations based on 2 variable values in a data step in SAS Data Management

selecting only certain observations based on 2 variable values in a data step

Hank — Sun, 09 Feb 2014 15:35:32 GMT

Hi,

I have a dataset that contains a variable for year (2010-2013), a variable for unitID (LT0100 to LT2400) and some other variables (a_1-a_8;b_1-b_8;etc...).

In a data step below, I want to create a new variable (f_5) based on (one variable divided by the sum of that variable), where the summary procedure is done given they all belong to the same year and same unit Id.

I think that I need to create some do-loops or macro variables, but I can´t figure out the specific coding. This is what I have tried:

proc sql;

select distinct unitID into :Unit separated by ', ' from Dataset1;

select distinct year into :year separated by ', ' from Dataset1;

quit;

data Dataset1;

set Dataset1;

if &unitID and &year then

a2_tot = sum(a_2);

f_5 = a_2/a2_tot;

drop a2_tot;

run;

Any suggestions on how to create the desired new variable?

Best regards,

Hank

Re: selecting only certain observations based on 2 variable values in a data step

art297 — Sun, 09 Feb 2014 17:32:50 GMT

Example have and want datasets are usually an easier way of showing the forum what you really want to achieve. From your description it appears like you only want to accomplish something like the following:

proc sql;

create table want as

select unitid,year,x,x/sum(x) as f_5

from have

group by unitid,year

;

quit;

Re: selecting only certain observations based on 2 variable values in a data step

Hank — Mon, 10 Feb 2014 08:08:49 GMT

Thanks for your reply! Here is a clarification:

In the dataset below, I have all the variables except f_5. I want to create f_5 as "a_2/SUM(a_2, where UnitID and year is the same and Code range between 1-6)".

In other words, I want to have the ratio of a specific code value, over the sum of all code values (except 0), for the variable a_2 for each specific UnitID and Year.

Preferably in a data step, since the creation of this new variable (f_5) is just one out of many more variables that needs to be created in ways similar to this one and I would prefer if all could be created in the same data step.

UnitId	Year	Code	a_1	a_2	a_3	f_5
LT0100	2010	0
LT0100	2010	1	2959139	320212	1600244	0,137518
LT0100	2010	2	4565010	142715	996557	0,06129
LT0100	2010	3	3301774	401540	2041513	0,172445
LT0100	2010	4	7384528	1163174	5855854	0,499536
LT0100	2010	5	1357620	33371	1125468	0,014332
LT0100	2010	6	1454282	267495	1110066	0,114878
LT0300	2010	0
LT0300	2010	1	649706	171904	326910	0,15413
LT0300	2010	2	1058760	97291	167824	0,087232
LT0300	2010	3	1156493	348738	733397	0,31268
LT0300	2010	4	2047786	415344	1444201	0,372399
LT0300	2010	5	257839	76602	174777	0,068682
LT0300	2010	6	248166	5440	241026	0,004878
LT0400	2010	0
LT0400	2010	1	478329	37400	224111	0,091693
LT0400	2010	2	745501	16167	65280	0,039637
LT0400	2010	3	705415	133909	542181	0,328304
LT0400	2010	4	901986	182750	712861	0,448047
LT0400	2010	5	175015	37655	112965	0,092319
LT0400	2010	6	185470		185470
LT0100	2011	0
LT0100	2011	1	2959139	352233,2	1600244	0,137518
LT0100	2011	2	4565010	156986,5	996557	0,06129
LT0100	2011	3	3301774	441694	2041513	0,172445
LT0100	2011	4	7384528	1279491	5855854	0,499536
LT0100	2011	5	1357620	36708,1	1125468	0,014332
LT0100	2011	6	1454282	294244,5	1110066	0,114878
LT0300	2011	0
LT0300	2011	1	649706	189094,4	326910	0,15413
LT0300	2011	2	1058760	107020,1	167824	0,087232
LT0300	2011	3	1156493	383611,8	733397	0,31268
LT0300	2011	4	2047786	456878,4	1444201	0,372399
LT0300	2011	5	257839	84262,2	174777	0,068682
LT0300	2011	6	248166	5984	241026	0,004878
LT0400	2011	0
LT0400	2011	1	478329	41140	224111	0,091693
LT0400	2011	2	745501	17783,7	65280	0,039637
LT0400	2011	3	705415	147299,9	542181	0,328304
LT0400	2011	4	901986	201025	712861	0,448047
LT0400	2011	5	175015	41420,5	112965	0,092319
LT0400	2011	6	185470		185470

Best regards,

Hank

Re: selecting only certain observations based on 2 variable values in a data step

TomKari — Mon, 10 Feb 2014 14:28:14 GMT

Hi, Hank

Thanks for the improved explanation.

While it is doable to accomplish everything you need in a single data step, it's fairly challenging. I would recommend Arthur's approach to get the summarized data first, in a step like this:

proc sql;

create table have_summ as

select UnitId, Year, sum(a_2) as Sum_a_2

from have

where Code > 0

group by UnitId, Year

order by UnitId, Year;

quit;

and then sort your original dataset:

proc sort data=have;

by UnitId Year;

run;

and then in your processing data step, you have access to the sum of a_2 as Sum_a_2, and can easily do your division, along with all of your other processing.

data want;

merge have have_summ;

by UnitId Year;

...

division, and other processing

...

run;

Re: selecting only certain observations based on 2 variable values in a data step

art297 — Mon, 10 Feb 2014 15:07:58 GMT

Like Tom said, sql will be a lot easier in this case and, in fact, can do everything in just a couple of lines. Here is the sql code and yet another way to do it in a datastep:

proc sql;

create table want as

select *,a_2/sum(a_2) as f_5

from have

group by unitid,year

order by year,unitid,code

;

quit;

/*or*/

proc sort data=have;

by unitid year code;

run;

data want (drop=sum_f_5);

do until (last.year);

set have (where=(code ne 0));

by unitid year;

sum_f_5=ifn(first.year,a_2,sum(sum_f_5,a_2));

end;

do until (last.year);

set have;

by unitid year;

f_5=a_2/sum_f_5;

output;

end;

run;

proc sort data=want;

by year unitid code;

run;