Also look at
?any
and
?all
Very handy functions.
Miguel
On Thu, Mar 11, 2010 at 12:37 PM, Esmail <esmail...@gmail.com> wrote:
> Hello all,
>
> I have two matrices, pop and pop2, each the same number of rows and
> columns that I want to compare for equality. I am concerned about
> efficiency in this operation.
>
> I've tried a few things without success so far. Doing something simple
> like:
>
> if (pop==pop2) { cat('equal') } else { cat('NOT equal') }
>
> results in the warning:
> 1: In if (pop == pop2) { :
> the condition has length > 1 and only the first element will be used
>
> so it seems to look only at the first element.
>
> print(pop==pop2) gives me a listing of TRUE/FALSE values for each
> element.
>
> I am really only looking for a single TRUE or FALSE value to tell me
> if the two populations (ie pop and pop2) are the same or different. In
> my application there will be about 200 columns and 50 rows and this
> comparison will happen very frequently (possibly a few thousand
> times), so I am concerned about efficiency.
>
> I am appending the code I used to generate my matrices and some things
> I tried (mentioned above) and also the output get so far.
>
> FWIW, Linux environment, R 2.10.1.
>
> Thanks,
> Esmail
>
> ps: Am I correct that if I do the assignment
>
> pop2 = pop
>
> I create a totally separate instance/(deep)copy of the
> data? I tried a few tests that seem to confirm this, but I'd
> rather be sure.
>
>
> ------- code ------------
>
> # create a binary vector of size "len"
> create_bin_Chromosome <- function(len)
> {
> sample(0:1, len, replace=T)
> }
>
> # create popsize members, each of length len
> create_pop_2 <- function(popsize, len)
> {
> datasize=len*popsize
>
> npop <- matrix(0, popsize, len, byrow=T)
>
> for(i in 1:popsize)
> npop[i,] = create_bin_Chromosome(len)
>
> npop
> }
>
>
> POP_SIZE = 3
> LEN = 8
>
> pop = create_pop_2(POP_SIZE, LEN)
> pop2 = pop
>
> print(pop==pop2)
> if (pop==pop2) { cat('equal\n') } else { cat('NOT equal\n') }
>
> print(pop)
> print(pop2)
>
> pop[2,5] = 99
> pop2[3,3] = 77
>
> print(pop==pop2)
> if (pop==pop2) { cat('equal\n') } else { cat('NOT equal\n') }
>
> print(pop)
> print(pop2)
>
> ------ output -----------
>
> > source('popc.R')
> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
> [1,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
> [2,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
> [3,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
> equal
> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
> [1,] 0 1 0 1 0 1 1 0
> [2,] 0 1 1 0 0 0 0 0
> [3,] 0 1 0 0 1 0 1 1
> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
> [1,] 0 1 0 1 0 1 1 0
> [2,] 0 1 1 0 0 0 0 0
> [3,] 0 1 0 0 1 0 1 1
> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
> [1,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
> [2,] TRUE TRUE TRUE TRUE FALSE TRUE TRUE TRUE
> [3,] TRUE TRUE FALSE TRUE TRUE TRUE TRUE TRUE
> equal
> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
> [1,] 0 1 0 1 0 1 1 0
> [2,] 0 1 1 0 99 0 0 0
> [3,] 0 1 0 0 1 0 1 1
> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
> [1,] 0 1 0 1 0 1 1 0
> [2,] 0 1 1 0 0 0 0 0
> [3,] 0 1 77 0 1 0 1 1
> Warning messages:
> 1: In if (pop == pop2) { :
> the condition has length > 1 and only the first element will be used
> 2: In if (pop == pop2) { :
> the condition has length > 1 and only the first element will be used
> >
>
> ______________________________________________
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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