Dear All,
I created a list (of length Z) in the following way:

my.array <- vector("list", Z)

then i assigned a matrix (of T rows by N columns) in each of the elements of
the list my.array in the following way:

my.array[[i]] <- matrix.data   ##( matrix.data has dimensions TxN, and i
repeated this command for i from 1 to Z, the matrix.data contains only
numeric data)

and
1. i would like to extract all the third columns of each of the Z matrices
stored in my.array (such that i get a new list only with the 3rd columns of
each matrix in the elements of a new list)

2. i would like to know how could i replace all the 3rd columns of each
matrix in my.array if i have a second matrix (size ZxT) with these columns.

is there a simple way to do these tasks? i appreciate any hints or advice.

Carlos

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