Find three most recent data year for each row

Question

I have a data set with one row for each country and 100 columns (10 variables with 10 data years each).

For each variable I am trying to make a new data set with the three most recent data years for that variable for each country (which might not be successive).

This is what I have so far, but I know its wrong because of the nest loop, and its has same value for recent1 recent2 recent3 however I haven't figured out how to create recent1 recent2 recent3 without two loops.

%macro test();  
   data Maternal_care_recent; 
   set wb;
   keep country MATERNAL_CARE_2004 -- MATERNAL_CARE_2013 recent_1 recent_2 recent_3;
 %let rc = 1;
    %do i = 2013 %to 2004 %by -1;
     %do rc = 1 %to 3 %by 1;
        %if MATERNAL_CARE_&i. ne . %then %do;
            recent_&rc. = MATERNAL_CARE_&i.;
        %end;
    %end;
%end; run; %mend; %test();

Answer 1

Thanks everyone. Found a hybrid solution from a few solutions posted.

data sample_ds;
infile datalines dlm=',';
input country $ maternal_2004 maternal_2005
maternal_2006 maternal_2007 maternal_2008 maternal_2009 maternal_2010        maternal_2011 maternal_2012 maternal_2013;
datalines;
MS,5,0,5,0,5,.,5,.,5,.
MW,3,9,5,0,5,0,5,.,5,0
WE,3,9,5,0,5,.,.,.,.,0
HU,2,0,5,.,5,.,5,0,5,0
MI,1,8,5,0,5,0,5,.,5,0
HJ,1,7,5,0,5,0,.,0,.,0
CJ,6,1,5,0,5,0,5,0,5,0
CN,6,1,.,5,0,5,0,5,0,5
CE,6,5,0,5,0,.,0,5,.,8
CT,2,5,0,5,0,5,0,5,0,9
CW,1,5,0,5,0,5,.,.,0,7
CH,0,5,0,5,0,.,0,.,0,5
;


%macro test(var);
data &var._recent; 
set sample_ds;
keep country  &var._1 &var._2 &var._3;
array mc {*} &var._2004-&var._2013;
array recent {*} &var._1-&var._25;
count=1;
do i = 10 to 1 by -1;

    if mc[i] ne . then do;
        recent[count] = mc[i];
        count=count+1;
    end;
end; 
run;
%mend;

Answer 2

When writing macro code, always keep in mind what has to be done when. SAS processes your code stepwise.

• Before your sas code is even compiled, your macro variables are resolved and your macro code is executed
• Then the resulting SAS Base code is compiled
• Finally the code is executed.

When you write %if MATERNAL_CARE_&i. ne . %then %do, this is macro code interpreded before compilation. At that time MATERNAL_CARE_&i. is not a variable but a text string containing a macro variable. The first time you run trhough your %do i = 2013 %to 2004 by -1, it is filled in as MATERNAL_CARE_2013, the second as MATERNAL_CARE_2012., etc. Then the macro %if statement is interpreted, and as the text string MATERNAL_CARE_1 is not equal to a dot, it is evaluated to FALSE and recent_&rc. = MATERNAL_CARE_&i. is not included in the code to pass to your compiler. You can see that if you run your code with option mprint;

The resolution;

options mprint;
%macro test();  
    data Maternal_care_recent; 
        set wb;
        keep country MATERNAL_CARE_: recent_:;
        ** The : acts as a wild card here **;

        %do i = 2013 %to 2004 %by -1;
            if MATERNAL_CARE_&i. ne . then do;
                %do rc = 1 %to 3 %by 1;
                    recent_&rc. = MATERNAL_CARE_&i.;
                %end;
            end;
        %end; 
    run; 
%mend; 
%test();

Now, before compilation of if MATERNAL_CARE_&i. ne . then do, only the &i. is evalueated and if MATERNAL_CARE_2013 ne . then do is passed to the compiler. The compiler will see this as a test if the SAS variable MATERNAL_CARE_1 has value missing, and that is just what you wanted;

Remark: It is not essential that I moved the if statement above the ``. It is just more efficient because the condition is then evaluated less often. It is however essential that you close your %ifs and %dos with an %end and your ifs and dos with an end;

Remark: you do not need %let rc = 1, because %do rc = 1 to 3 already initialises &rc.;

For completeness SAS is compiled stepwise: The next PROC or data step and its macro code are only considered when the preveous one is executed. That is why you can write macro variables from a data step or sql select into that will influence the code you compile in your next step, somehting you can not do for instance with C++ pre compilation;

Answer 3

Maybe I don't get your request, but according to your description: "For each variable I am trying to make a new data set with the three most recent data years for that variable for each country (which might not be successive)" I created this sample dataset with dt1 and dt2 and 2 locations.

The output will be 2 datasets (and generally the number of the variables starting with DT) named DS1 and DS2 with 3 observations for each country, the first one for the first variable, the second one for the second variable.

This is the sample dataset:

data sample_ds;
length city $10 dt1 dt2 8.;
infile datalines dlm=',';
input city $ dt1 dt2;
datalines;
MS,5,0
MS,3,9
MS,3,9
MS,2,0
MS,1,8
MS,1,7
CA,6,1
CA,6,.
CA,6,.
CA,2,8
CA,1,5
CA,0,4
;

This is the sample macro:

%macro help(ds=);

data vars(keep=dt:); set &ds; if _n_ not >0; run;
%let op = %sysfunc(open(vars));
%let nvrs = %sysfunc(attrn(&op,nvars));
%let cl = %sysfunc(close(&op));

%do idx=1 %to &nvrs.;
proc sort data=&ds(keep=city dt&idx.) out=ds&idx.(where=(dt&idx. ne .)) nodupkey; by city DESCENDING dt&idx.; run;
data ds&idx.; set ds&idx.;
retain cnt;
by city DESCENDING dt&idx.;
if first.city then cnt=0; else cnt=cnt+1;
run;
data ds&idx.(drop=cnt); set ds&idx.(where=(cnt<3)); rename dt&idx.=act&idx.; run;
%end;

%mend;

You will run this macro with:

%help(ds=sample_ds);

In the first statement of the macro I select the variables on which I want to iterate:

data vars(keep=dt:); set &ds; if _n_ not >0; run;

Work on this if you want to make this work for your code, or simply rename your variables as DT1 DT2...

Let me know if it is correct for you.

Answer 4

You don't need to use a macro to do this - just some arrays:

data Maternal_care_recent; 
   set wb;
   keep country MATERNAL_CARE_2004-MATERNAL_CARE_2013 recent_1 recent_2 recent_3;
   array mc {*} MATERNAL_CARE_2004-MATERNAL_CARE_2013;
   array recent {*} recent1-recent3;
    do i = 2013 to 2004 by -1;
     do rc = 1 to 3 by 1;
        if mc[i] ne . then do;
            recent[rc] = mc[i];
        end;
    end;
run;