topic Re: A problem on vector manipulation in SAS/IML Software and Matrix Computations

A problem on vector manipulation

milanxiaoyao — Fri, 20 Apr 2012 13:02:14 GMT

Hi all

I have a quick question and I have been struggling for several days. I hope you could help me. Many thanks.

I hope to design a vector as follows: suppose there are two given vector a=[2 3 5], b=[1 2 3]
Here b indicates the frequency vector. I hope to generate a vector c=[2 3 3 5 5 5]. I am trying to use the repeat function in IML, but there is always something wrong

Thanks

Re: A problem on vector manipulation

Rick_SAS — Fri, 20 Apr 2012 14:01:59 GMT

Use the CUSUM function to get the indexes into a long vector that has sum(b) elements. Loop over the categories and use the REPEAT functions to fill up the vector:

proc iml;

a = {2 3 5};

b = {1 2 3};

cumFreq = 0 || cusum(b);

N = ncol(a);

v = j(sum(b), 1);

do i = 1 to N;

bIdx = 1 + cumFreq; /* begin index */

eIdx = cumFreq[i+1]; /* end index */

print i bIdx eIdx;

v[bIdx:eIdx] = repeat(a, b);

end;

print v;

Re: A problem on vector manipulation

milanxiaoyao — Fri, 20 Apr 2012 15:02:07 GMT

Hi Rick

Many thanks. This is great ! And the function cusum( ) is extremely helpful !