I have a set of vectors that i generate by randomly sampling from a larger vector (the item are words/characters).
I do it in a do loop and after each iteration i have a 1*4 or a 1*3 vector. I would like to collect all of these vectors into a matrix whose size is N*4, where N is the number of loops. In cases where the vectors are 1*3, the last item in a row of a matrix will be missing. I was hoping to initially create a N*4 matrix of zeros, and after each loop, insert the vector (either the 1*3 or 1*4) in row i, where i go from 1 to N.
Can anyone suggest an efficient code for implementing this task?
Thanks for your help,
Tzachi
It would have been useful for you to have posted your code.
Because you are storing character values, you can't allocate a numerical matrix of zeros. Instead you need to allocate a character matrix of blank strings. See the article "How to create a string of a specified length" for tips about how to create a matrix that contains a matrix that contains all blank strings. Then inside the loop you look at the number of elements of each sample and assign it to columns 1:3 or 1:4 of the i_th row, as follows:
proc iml;
call randseed(1234);
list = {peter piper picked a peck of pickled peppers};
N = 10;
/* determine number of items */
numItems = sample({3 4}, N);
print numItems;
/* Allocate matrix for results. See
http://blogs.sas.com/content/iml/2014/05/12/how-to-create-a-string-of-a-specified-length-in-sasiml.html */
results = j(N, 4, BlankStr(nleng(list)));
do i = 1 to N;
items = sample(list, numItems[i]);
results[i, 1:ncol(items)] = items;
end;
print results;
It would have been useful for you to have posted your code.
Because you are storing character values, you can't allocate a numerical matrix of zeros. Instead you need to allocate a character matrix of blank strings. See the article "How to create a string of a specified length" for tips about how to create a matrix that contains a matrix that contains all blank strings. Then inside the loop you look at the number of elements of each sample and assign it to columns 1:3 or 1:4 of the i_th row, as follows:
proc iml;
call randseed(1234);
list = {peter piper picked a peck of pickled peppers};
N = 10;
/* determine number of items */
numItems = sample({3 4}, N);
print numItems;
/* Allocate matrix for results. See
http://blogs.sas.com/content/iml/2014/05/12/how-to-create-a-string-of-a-specified-length-in-sasiml.html */
results = j(N, 4, BlankStr(nleng(list)));
do i = 1 to N;
items = sample(list, numItems[i]);
results[i, 1:ncol(items)] = items;
end;
print results;
Thanks very much Rick!
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