Sas renaming variable with do loop and if then condition

I'm trying to rename variables x0 - x40 so that x0 will become y_q1_2014, x1 will become y_q4_2013, x2 will become y_q3_2013 and so on till x40 that will become y_q1_2004.

I want my new variable to display in its name the quarter and year of the observation. Now I have the following macro in SAS that is not working properly: the values of j and k are not changing according to the if - then condition. What am i doing wrong?

%macro rename(data);

%let j=1;
%let k=2014;

%do i = 0 %to 40 %by 1;

    data mydata;
    set &data.; 

    y_q&j._&k. = x&i.;

    if &j.=1 then do k = &k.-1 and j = 4;

    else do j=&j.-1;

    run;

%end;

%mend;

Solution

This will likely be easier to do using the data step rather than a macro loop (as most things are!).

In this case, you have two problems:

How to mass-rename variables
How to convert x# to y_q#_####

An easy way to rename variables is to create a dataset with the variable names as rows, then create the new variable names. You can then pull that into a rename list very easily.

So something like this would do that.

*Create dataset with names in it. 
data names;
set sashelp.vcolumn;
where memname='HAVE' and libname='WORK' and name =: 'X';
keep name;
run;

*some operation to determine new_name needs to go in that dataset also - coming later;


*Now create a list of rename macro calls.
proc sql;
 select cats('%rename(var=',name,',newvar=',new_name,')')
 into :renamelist separated by ' '
 from names;
quit;

*Here is the simple rename macro.
%macro rename(var=,newvar=);
 rename &var.=&newvar.;
%mend rename;

*Now do the renames.  Can also go in a data step.
proc datasets lib=work;
modify have;
&renamelist.
quit;

How to convert is a more interesting question, and begs the question: is this a one time thing, or is this a repeated process? If it's a repeated process, does X0 always mean the most recent quarter in the data, or does it always mean q1 2014?

Assuming it is always the most recent quarter, you can use intnx to do this.

%let initdate='01JAN2014'd;

data have;
do x = 0 to 40;
  qtr = intnx('QUARTER',&initdate,-1*x);
  format qtr YYQ.;
  output;
end;
run;

You can thus use this code (the portion inside the do loop, operating on an x that you pull out of the name in the dataset) in the earlier names data step to create new_name however you want. You might use the YYQ format in your new name if you have flexibility here (as it's standard, and the easiest solution). Otherwise, you would want to pull this apart either using put and then substring, or quarter() and year() functions off of the date variable here.