[R] rbind-ing numeric matrices

[Sarah Goslee]

Hi Nick,

On Tue, May 1, 2012 at 1:56 PM, Nick Switanek <nswitanek at gmail.com> wrote:
> Thank you, Steve and Sarah, for your swift replies.
>
> I didn't know about dput(). class() returns "matrix" for A, B, and C, but
> here:
>
>> class(A)
> [1] "matrix"
>> class(B)
> [1] "matrix"
>> dput(A)
> structure(list(1239814462, 1239814601, 14349, 3, 4, 0, 12, 46601,
>    17801, 12401, 106001), .Dim = c(1L, 11L), .Dimnames = list(
>    NULL, c("a", "b", "c", "d", "e", "f", "g", "h", "i", "j",
>    "k")))

I'm not sure how you created A, but it's a list - see the structure
given by dput(), and also:

> is.list(A)
[1] TRUE
> is.list(B)
[1] FALSE


>> dput(B)
> structure(c(1239197400, 1239199200, 1239202800, 1239199199, 1239202799,
> 1239206399, 14342, 14342, 14342, 3, 3, 3, 0, 0, 0, 0, 0, 0, 9,
> 10, 11, 35999, 39599, 43199, 7199, 10799, 14399, 1799, 5399,
> 8999, 1799, 5399, 8999), .Dim = c(3L, 11L), .Dimnames = list(
>    NULL, c("a", "b", "c", "d", "e", "f", "g", "h", "i", "j",
>    "k")))

Note that the structure for B doesn't say anything about it being a list.

In this particular case, you can fix that with:
> rbind(unlist(A), B)
              a          b     c d e f  g     h     i     j      k
[1,] 1239814462 1239814601 14349 3 4 0 12 46601 17801 12401 106001
[2,] 1239197400 1239199199 14342 3 0 0  9 35999  7199  1799   1799
[3,] 1239199200 1239202799 14342 3 0 0 10 39599 10799  5399   5399
[4,] 1239202800 1239206399 14342 3 0 0 11 43199 14399  8999   8999

But now I'm curious where A came from.

Sarah

>> C <- rbind(A,B)
>> dput(C)
> structure(list(1239814462, 1239197400, NULL, NULL, 1239814601,
>    1239199200, NULL, NULL, 14349, 1239202800, NULL, NULL, 3,
>    1239199199, NULL, NULL, 4, 1239202799, NULL, NULL, 0, 1239206399,
>    NULL, NULL, 12, 14342, NULL, NULL, 46601, 14342, NULL, NULL,
>    17801, 14342, NULL, NULL, 12401, 3, NULL, NULL, 106001, 3,
>    NULL, NULL), .Dim = c(4L, 11L), .Dimnames = list(NULL, c("a",
> "b", "c", "d", "e", "f", "g", "h", "i", "j", "k")))
>
> But how do I convert A to the appropriate form for rbinding? Not simply
> with as.matrix(). Witness:
>> dput(as.matrix(A))
> structure(list(1239814462, 1239814601, 14349, 3, 4, 0, 12, 46601,
>    17801, 12401, 106001), .Dim = c(1L, 11L), .Dimnames = list(
>    NULL, c("a", "b", "c", "d", "e", "f", "g", "h", "i", "j",
>    "k")))
>
> I think we're closer but I still need your help!
>
> Nick
>
>
> On Tue, May 1, 2012 at 12:02 PM, Steve Lianoglou <
> mailinglist.honeypot at gmail.com> wrote:
>
>> Hi,
>>
>> On Tue, May 1, 2012 at 11:52 AM, Nick Switanek <nswitanek at gmail.com>
>> wrote:
>> > Good morning,
>> >
>> > I'm running into trouble rbind-ing numeric matrices with differing
>> numbers
>> > of rows. In particular, there seem to be issues whenever a one-row
>> numeric
>> > matrix is involved.
>> >
>> > Assume A is a numeric matrix with 1 row and Y columns and B is a numeric
>> > matrix with X rows and Y columns. Let C be the result of rbinding A and
>> B.
>> > Then C is a numeric matrix with X + 1 rows and Y columns, only instead of
>> > the rows of B being "stacked" beneath the row of A as expected, the
>> first Y
>> > elements of the 1st column of B are placed in the 2nd row of C, the
>> > remaining values of B are discarded, and NULL values fill out the rest of
>> > the matrix C.
>> >
>> > The number of columns of A and B match. The colnames of A and B match.
>> Both
>> > are numeric matrices. I've pored over the rbind/cbind documentation but
>> > can't identify why I'm getting this behavior from rbind. I'd be extremely
>> > grateful for your suggestions or thoughts.
>>
>> If everything you say is true (and I'm understanding what you're
>> saying), there must be something else going on with your data.
>> Consider:
>>
>> R> m1 <- matrix(-(1:5), nrow=1)
>> R> m2 <- matrix(1:20, ncol=5)
>> R> rbind(m1, m2)
>>      [,1] [,2] [,3] [,4] [,5]
>> [1,]   -1   -2   -3   -4   -5
>> [2,]    1    5    9   13   17
>> [3,]    2    6   10   14   18
>> [4,]    3    7   11   15   19
>> [5,]    4    8   12   16   20
>>
>> Can you provide a small example of your data that reproduces the
>> problem you're seeing?
>>
>> Construct these objects in your workspace and copy/paste the output of
>> dput on your m1 and m2 matrices so we can easily work w/ them.
>>
>> Cheers,
>> -steve
>>


-- 
Sarah Goslee
http://www.functionaldiversity.org