[R] 3 questions regarding matrix copy/shuffle/compares

[Esmail]

David,

Good news! It seems that R has deep copy by default. I ran this simplified
test and it seems I can change 'pop' without changing the saved version.

POP_SIZE = 4
LEN = 8
pop=create_pop_2(POP_SIZE, LEN)
cat('printing original pop\n')
print(pop)

keep_pop = pop
pop[1,1] = 99

cat('printing changed pop\n')
print(pop)
cat('printing keep_pop\n')
print(keep_pop)



-----------

 > source('mat.R')
[1] 32
printing original pop
      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
[1,]    0    1    1    0    1    0    0    1
[2,]    1    0    1    0    0    0    1    1
[3,]    0    1    0    1    1    1    0    1
[4,]    0    0    0    1    0    1    0    0
[5,]    0    0    0    0    0    0    0    0
[6,]    0    0    0    0    0    0    0    0
[7,]    0    0    0    0    0    0    0    0
[8,]    0    0    0    0    0    0    0    0


printing changed pop
      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
[1,]   99    1    1    0    1    0    0    1
[2,]    1    0    1    0    0    0    1    1
[3,]    0    1    0    1    1    1    0    1
[4,]    0    0    0    1    0    1    0    0
[5,]    0    0    0    0    0    0    0    0
[6,]    0    0    0    0    0    0    0    0
[7,]    0    0    0    0    0    0    0    0
[8,]    0    0    0    0    0    0    0    0


printing keep_pop
      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
[1,]    0    1    1    0    1    0    0    1
[2,]    1    0    1    0    0    0    1    1
[3,]    0    1    0    1    1    1    0    1
[4,]    0    0    0    1    0    1    0    0
[5,]    0    0    0    0    0    0    0    0
[6,]    0    0    0    0    0    0    0    0
[7,]    0    0    0    0    0    0    0    0
[8,]    0    0    0    0    0    0    0    0


Re Shuffle

I tried using sample based on your earlier post, but your example
really helped, thanks!  That solves the shuffling issue.

dx <- sample(1:POP_SIZE, POP_SIZE)
cat('shuffled index:')
print(dx)
print(pop[dx,])

cat('shuffled pop')
pop[1:POP_SIZE,] = pop[dx,]
print(pop)


re compare:

 > I am unclear why you would not create an original and a copy,

Well .. that I wanted to do from the start (hence my question about
deep copy :-)

 > work on the copy, and compare with the original that is also sorted
 > by the external index.

That's a great idea, hadn't thought of keeping the index around for
this, I'll give this a try.

Final question, how do I compare these two structures so that I get
one result, true or false? Right now

keep == pop yields all these individual comparisons:

 > pop==keep

       [,1] [,2]  [,3] [,4]  [,5]
[1,] FALSE TRUE FALSE TRUE FALSE
[2,] FALSE TRUE FALSE TRUE FALSE
[3,]  TRUE TRUE  TRUE TRUE  TRUE
[4,]  TRUE TRUE  TRUE TRUE  TRUE
[5,]  TRUE TRUE  TRUE TRUE  TRUE
[6,]  TRUE TRUE  TRUE TRUE  TRUE

Thanks for the help, much appreciated.

Esmail