ERROR: The ID value occurs twice in the same BY group in Proc Transpose

[Spintu]

proc transpose data=test out=want (drop=_:) prefix=o_;
var o_value;
by subject crs;
id var;
run.

subject	crs	var	value	o_value
101	0	thresp
101	998	thresp	NE	NE
101	998	thresp	PD	PD

here I have attached the code and sample data. However, I am getting the below error messages. 

ERROR: The ID value "o_tlresp" occurs twice in the same BY group.

can someone help me to fix this? 

[Tom · Accepted solution]

Sure.  What output do you WANT to get in that situation?

Do you want just the FIRST (or LAST) value in the group?  If so then first get rid of the unwanted observations.

data for_transpose;
  set test;
  by subject crs var;
  if first.var;
run;
proc transpose data=for_transpose out=want (drop=_:) prefix=o_;
  var o_value;
  by subject crs;
  id var;
run.

Do you want ALL of the observations?  Then you need to add a new variable.

data for_transpose;
  set test;
  by subject crs var;
  if first.var then row=0;
  row+1;
run;

Do you want them to become new OBSERVATIONS? Then include the new variable in the BY statement.

proc transpose data=for_transpose out=want (drop=_:) prefix=o_;
  var o_value;
  by subject crs row;
  id var;
run.

Do you want them to become new VARIABLES? Then include the new variable in the ID statement.

proc transpose data=for_transpose out=want (drop=_:) prefix=o_;
  var o_value;
  by subject crs;
  id var row;
run.

[Spintu]

I am looking for ALL of the observations in the output.