topic Re: how to insert new rows into vectors or matrix in SAS/IML Software and Matrix Computations

how to insert new rows into vectors or matrix

trekvana — Thu, 09 Sep 2010 01:55:18 GMT

hello all,

how can I augment a vector or matrix with proc iml?

for example, lets say i have a vector x={1,2} and I want to augment x to a 4x1 vector with missing value indictor (.) in positions 2 and 3. in other words i want x=(1, . , . , 2}. is this possible to do??

pretty much i have an x vector and i also have an index vector (i={2,3} in this example) with the positions i want to include the (.) character.

Re: how to insert new rows into vectors or matrix

Rick_SAS — Thu, 09 Sep 2010 10:17:34 GMT

The easiest way is to allocate a matrix of missing values and then fill in the nonmissing values by using subscripts. Suppose your data look like this:

N = 4; /** number of rows after including missing values **/
MissingIdx = {2, 3}; /** indices of rows that contain missing **/
x = {1,2}; /** data values **/

The hard part is that you need to know the indices of the NONmissing observations, which you can find by using the SETDIF function. The function is explained at
http://support.sas.com/documentation/cdl/en/imlug/59656/HTML/default/langref_sect241.htm

NMidx = setdif(1:N, MissingIdx); /** find the indices for nonmissing values **/
newX = repeat(., N); /** create answer vector with all missings **/
newX[NMidx] = x; /** assign nonmissing values in the specified locations **/
print newX;

Re: how to insert new rows into vectors or matrix

trekvana — Thu, 09 Sep 2010 16:37:55 GMT

Thanks Rick!