Dimension of a vector

Consider the following:
A <- 1:10
A
[1]  1  2  3  4  5  6  7  8  9 10
dim(A)
NULL
dim(A) <- c(2,5)
A
[,1] [,2] [,3] [,4] [,5]
[1,]    1    3    5    7    9
[2,]    2    4    6    8   10
dim(A)
[1] 2 5
dim(A) <- 10
A
[1]  1  2  3  4  5  6  7  8  9 10
dim(A)
[1] 10

Would it not make sense to have dim(A) = length(A) for all vectors?

Murray
Dr Murray Jorgensen      http://www.stats.waikato.ac.nz/Staff/maj.html
Department of Statistics, University of Waikato, Hamilton, New Zealand
Email: maj at waikato.ac.nz                                Fax 7 838 4155
Phone  +64 7 838 4773 wk    Home +64 7 825 0441    Mobile 021 1395 862
In R, vectors don't have dimensions, arrays do.
x <- c(1, 4, 5)
class(x)
[1] "numeric"
y <- array(x)
class(y)
[1] "array"
dim(x)
NULL
dim(y)
[1] 3
Consider the following:
A <- 1:10
A
 [1]  1  2  3  4  5  6  7  8  9 10
dim(A)
NULL
dim(A) <- c(2,5)
A
    [,1] [,2] [,3] [,4] [,5]
[1,]    1    3    5    7    9
[2,]    2    4    6    8   10
dim(A)
[1] 2 5
dim(A) <- 10
A
 [1]  1  2  3  4  5  6  7  8  9 10
dim(A)
[1] 10

Would it not make sense to have dim(A) = length(A) for all vectors?

Murray
--
Dr Murray Jorgensen      http://www.stats.waikato.ac.nz/Staff/maj.html
Department of Statistics, University of Waikato, Hamilton, New Zealand
Email: maj at waikato.ac.nz                                Fax 7 838 4155
Phone  +64 7 838 4773 wk    Home +64 7 825 0441    Mobile 021 1395 862

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Consider the following:
A <- 1:10
A
[1]  1  2  3  4  5  6  7  8  9 10
dim(A)
NULL
dim(A) <- c(2,5)
A
    [,1] [,2] [,3] [,4] [,5]
[1,]    1    3    5    7    9
[2,]    2    4    6    8   10
dim(A)
[1] 2 5
dim(A) <- 10
A
[1]  1  2  3  4  5  6  7  8  9 10
dim(A)
[1] 10

Would it not make sense to have dim(A) = length(A) for all vectors?
No.  A one-dimensional array and a vector are not the same thing.
There are subtle differences, such as what names() means (see ?names).

That a 1D array and a vector _print_ in the same way does occasionally 
lead to confusion, but then you also cannot tell from your printout that A 
has type "integer" and not "double".
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595