topic Re: Matrix with strings in IML in SAS/IML Software and Matrix Computations

Matrix with strings in IML

philip_ — Thu, 18 May 2017 09:29:49 GMT

I wanted to create a matrix with nested loops where elements have numeric values but also concatenated string values, however I get this error: "ERROR: (execution) Invalid argument to function."

I built a small example that expresses the problem:

proc iml;
/* data example */
pds = {0.3, 0.4, 0.8};

M = J(3,1,0);
do i=1 to 3;
M[i,1] = 'PD' + char(pds[i]);
end; 

print M;
quit;

As I understand it: it is not possible to write a string to a matrix element?

Thank you for suggestions how to solve this!

Re: Matrix with strings in IML

IanWakeling — Thu, 18 May 2017 09:35:22 GMT

The matrix M would have to be defined as a character for this to work. For example:

proc iml;
/* data example */
pds = {0.3, 0.4, 0.8};

M = J(3,1,'       ');
do i=1 to 3;
M[i,1] = 'PD' + char(pds[i],4,1);
end; 

print M;
quit;

But surely this makes it difficult to recover the numeric value later on. So why not have one numeric and one character matrix?

Re: Matrix with strings in IML

philip_ — Thu, 18 May 2017 09:51:47 GMT

Ian, thank you! This helps a lot, but brings up two related questions:

- is it possible to have a mixed matrix within IML (i.e. one column is numeric, and one character) ?

- do I need to print the blank spaces (' ') in the initialization of the matrix or is there also a shortcut?

(Regarding your suggestion with the two separate matrices: this is just some "weird" flag that is required, the numerical value would still be given in an additional column)

Thanks!

Re: Matrix with strings in IML

Rick_SAS — Thu, 18 May 2017 10:02:26 GMT

As Ian says, please tell us what you are trying to accomplish. The easiest approach might be to have a matrix of "values" and another matrix of "labels",

In answer to your question, matrices are either ALL NUMERIC or ALL CHARACTER. However, SAS/IML supports the "Table" data structure, which is like an in-memory version of a data set. A table can contain columns of either data type. Tables are new in SAS/IML 14.2 (SAS 9.4m4).

Re: Matrix with strings in IML

IanWakeling — Thu, 18 May 2017 10:09:58 GMT

Regarding the other question :

M = J(3,1,BlankStr(6));

would be a way of declaring a character matrix with a specific string length.

Re: Matrix with strings in IML

Ksharp — Thu, 18 May 2017 12:18:11 GMT

proc iml;
/* data example */
pds = {0.3, 0.4, 0.8};

M = 'PD ' + strip(char(pds));


print M;
quit;