How can I get the if then statement to do nothing in one of the cases?

[DJ20]

Hi everyone,

I am using an if statement in SAS/IML. I want the program to do nothing if b = 1 else to run some calculations. Is there a way to tell SAS to do nothing in the first part of the if statement as follows:

if b = 1

 then do (nothing)

   else do i = 1 to b;

     .

     .

     .

end;

I have tried to do it the other way around:

if b ~= 1

  then do i = 1 to b;

     .

     .

     .

end;

else do nothing!

However SAS is not recognizing the not equal (~=) sign. I am not sure if its the correct operator anyway.

Any suggestions would be greatly appreciated.

regrds,

DJ

[PaigeMiller]

Change your logic, only take action if b>1

if b > 1 then do i = 1 to b;

     .

     .

     .

end;

In PROC IML, not equal is ^= 

[DJ20]

hi @PaigeMiller 

thanks for your reply.

I was trying to add the values of each column in a matrix if the number of columns, b, is greater than one. 

What I did is I specified an array TB = j(b,1,0);

then I added my IF statement 

if b > 1 then do i = 1 to b;

     .

     .

     .

end;print TB;

because I initially sat the array entries to 0's when b is not equal to 1 it prints the value of 0 for TB but I want it to print nothing. I want it to ignore the calculations if b is greater than 1.

thanks,

DJ

[PaigeMiller]

I am having problems understanding your comments here, it's not clear to me if you are still having a problem or if you are just making comments. Can you please clarify?

You don't need loops to sum columns in PROC IML.

https://documentation.sas.com/?docsetId=imlug&docsetTarget=imlug_workmatrix_sect025.htm&docsetVersio...

[DJ20]

Hi @PaigeMiller,

Ignore the fact that I am using a loop I can change that. In fact I did change it to the following:

if b > 1
then TB = data[+,];
print TB;

I am adding the elements of each column only if the number of columns, b, is greater than 1. The IF statement I used works however when the number of columns = 1, its giving me an error message as I have asked the program to print TB however haven't told the program what to do if b < 1. So it doesn't know what to print for TB.

ERROR: Matrix TB has not been set to a value.

obviously, if I take the last line off (print TB;) the error disappears.

I hope you understand my problem now.

Thanks,

DJ

[PaigeMiller]

A simple fix:

if b > 1 then do;
    TB = data[+,];
    print TB;
end;

[DJ20]

hi @PaigeMiller 

Great, that works. Thanks a lot mate.

regards,

DJ