Cropping a matrix by rows

I assiduously avoid automatically generating distinct objects, and recommend that you also do so.
You have the data, and can refer to individual rows by index as you need them.
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Sent from my phone. Please excuse my brevity.

Hello r-help,

I've been banging my head against the computer in an attempt to learn
how
to divide my matrix into segments by rows. I want to be able to return
each
segment as a newly named object.  I've tried looking at the apply
functions
and creating a for loop but brain no work.  Here's the basic starting
objects that I believe would be needed to separate the matrix.

mat <- matrix(c(1:40),10,4)
rowcropping <- sort(sample(2:9,2))
rowcropping <- c(1,rowcropping,length(mat[,1]))
mat[rowcropping[1]:rowcropping[2],]

I want something like the last line as the first object but getting
them
all by automation  as separate objects is my goal.  Thanks.

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