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From "Frederick R Reiss" <>
Subject Re: Combining Multiple Matrix
Date Tue, 02 May 2017 23:44:59 GMT

Hi Arijit,

Have you considered using parfor and left indexing? Here's an example from
the docs that generates a large matrix out of smaller chunks:

ms = matrix(0, rows=2, cols=3*10)
parfor (v in 1:10, check=0) {
    mv = matrix(v, rows=2, cols=3)
    ms[,(v-1)*3+1:v*3] = mv

SystemML has a special data structure to represent a matrix block that is
all zeros, so creating a very large matrix of zeros (first line in the
above listing) is an inexpensive operation.


From:	arijit chakraborty <>
To:	""
Date:	05/02/2017 09:48 AM
Subject:	Combining Multiple Matrix


Our process is generating multiple matrix, of same size, but number of
matrix is random. Finally, we combine all the smaller matrix to get a final
large matrix.

The way we are creating the large matrix is, we are creating a blank matrix
and then update the matrix once each smaller matrix is created. This is
inefficient because we are initially creating a large matrix, which
sometimes take more than required space.

So is there any method where we can combined all the final smaller matrix
together into a larger matrix? For rbind and cbind, we have to use loops to
merge the matrix.

Thank you!


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