MACROS and IML

[ejohnson96]

I am trying to write this macro to calculate the hand value of cards, however I keep getting the below error. Any suggestions?

%macro handValue(cards=);

    proc iml;
    use &cards;
    read all into cards;
    value = cards[ ,+];
    %do i = 1 %to ncol(&cards);
        %if(cards[i] = 1 & value <= 11) %then %do;
        value = value + 10;
        print value;
        %end;
    %end;
        %if(value > 21) %then print 0;
        %else %if(value = 21 & ncol(cards) = 2) %then print 21.5;
        %else print value;
        quit;

%mend;

ERROR: Required operator not found in expression: nol(&cards)
ERROR: The %TO value of the %DO I loop is invalid.
ERROR: The macro HANDVALUE will stop executing.

[Rick_SAS]

Remember that the macro language writes SAS code.  Because you have loops and subscripts in the SAS/IML language you ALMOST NEVER need to use macro %DO loops.  You can write this in straight IML.  

I think there are logical problems with your code, but that is to be expected since you haven't been able to run/debug it. Rather than trying to figure out what you are trying to do, here is some code that runs that you can then debug:

proc iml;
use &cards;
read all into cards;
close &cards;
value = cards[ ,+];
print cards value;
do i = 1 to ncol(cards);  /* OR nrow(cards) ?? */
   if(cards[i] = 1 & value <= 11) then do;
      value = value + 10;
      print value;
   end;
end;
if(value > 21) then print 0;
else if(value = 21 & ncol(cards) = 2) then /* or nrow(cards)??? */
    print 21.5;
else print value;

One thing for you to think about: is the 'cards' variable a row vector, a column vector, or a matrix (each row of which is a hand)? If it is a matrix, then cards[i] is not going to make sense.

[ejohnson96]

When I run this code:

proc iml;
use test_cards;
read all into cards;
value = cards[,+];
do i = 1 to ncol(cards);
if(cards[i] = 1 & value <= 11) then do;
value = value + 10;
print value;
end;
end;
if(value > 21) then print 0;
else if(value = 21 & ncol(cards) = 2) then print 21.5;
else print value;
quit;

the program works.

However I need it to be in a macro because I need to be able to put in any hand of cards and compute the value. 

[Rick_SAS]

That's fine. Lots of people embed SAS/IML in a macro to pass in parameters such as data set names.  My point is that you don't need %DO and %IF statements.

%macro handValue(cards=);

    proc iml;
    use &cards;

...

%mend;