[R] Copying matrices with certain probabilities
William Aue
william.aue at gmail.com
Sun Oct 4 15:36:55 CEST 2009
Hi all! Below is the problem I am struggling with.
Let’s say I have a matrix (x) of values:
# [,1] [,2] [,3] [,4]
#[1,] 1 3 2 1
#[2,] 2 1 3 2
I need to copy the items into a new matrix (y) with certain
probability guidelines. I need to set it up such that:
1. for each item there is a probability (a) that the item will or will
not be copied at all from x to y. If nothing is copied then the
corresponding value in y should be 0.
2. If something is copied from x to y, then there should be a separate
probability (b) that the items will be correctly copied to y with
items that are incorrectly copied being randomly drawn from a
geometric distribution.
So y may look like the below example. Row 1 shows that [1,2] was
copied and subsequently correctly copied but nothing else in [1,] was
copied. In [2,], [2,1] was copied but subsequently incorrectly copied,
[2,2] & [2,3] were not copied at all, and [2,4] was copied and
correctly copied.
# [,1] [,2] [,3] [,4]
#[1,] 0 3 0 0
#[2,] 5 0 0 2
I would also like to setup a loop for this process wherein if
something doesn’t get copied at all during a previous pass, then there
is the opportunity for it to be copied on a second/third/etc pass.
I hope this is clear enough. I am still a novice at R, so any
help/guidance that can be offered will be greatly appreciated.
Best,
Billy Aue
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