R devel - Sep 2002 - matrices and arrays loose dimension after multiplying with scalar (PR#1979)

A matrix or array with one of its dimensions having zero elements looses its
dimension after multiplying with scalar.
Admittedly this is an extreme case, however it DOES make sense to retain an
objects formal structure after multiplying with a scalar, as e.g. a matrix
with zero rows IS a legal object in S. BTW, the prototype does retain the
dimension.

Best


Jens Oehlschlägel


# replication code at the end


# R1.5.1
> m <- matrix(1, nrow=0, ncol=3)
> m
     [,1] [,2] [,3]
> m*100
numeric(0)
> 
> m <- matrix(1, nrow=3, ncol=0)
> m
> m*100
numeric(0)
> 
> a <- array(1, dim=c(2, 2, 0))
> a
> a*100
numeric(0)


# Prototype
> m <- matrix(1, nrow=0, ncol=3)
> m
integer matrix: 0 rows, 3 columns.
> m*100
integer matrix: 0 rows, 3 columns.
>
> m <- matrix(1, nrow=3, ncol=0)
> m
integer matrix: 3 rows, 0 columns.
> m*100
integer matrix: 3 rows, 0 columns.
>
> a <- array(1, dim=c(2, 2, 0))
> a
integer array: 2 by 2 by 0
> a*100
integer array: 2 by 2 by 0



# replication code

m <- matrix(1, nrow=0, ncol=3)
m
m*100

m <- matrix(1, nrow=3, ncol=0)
m
m*100

a <- array(1, dim=c(2, 2, 0))
a
a*100

> version
         _              
platform i386-pc-mingw32
arch     i386           
os       Win32          
system   i386, mingw32  
status                  
major    1              
minor    5.1            
year     2002           
month    06             
day      17             
language R    

-- 




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>>>>> "JensOe" == oehl list <oehl_list@gmx.de>
>>>>>     on Tue, 3 Sep 2002 17:45:33 +0200 (MET DST) writes:
    JensOe> A matrix or array with one of its dimensions having
    JensOe> zero elements looses its dimension after multiplying
    JensOe> with scalar.  Admittedly this is an extreme case,
    JensOe> however it DOES make sense to retain an objects
    JensOe> formal structure after multiplying with a scalar, as
    JensOe> e.g. a matrix with zero rows IS a legal object in
    JensOe> S. BTW, the prototype does retain the dimension.

    JensOe> Best

Danke, Jens!

o still happens in R-devel (aka 1.6.0 "unstable") of today.

o yes, it's a bug  though not a high-priority one {and we are
  approaching deep feature freeze real soon now...}


Martin




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