R help - Jul 2009 - subscript into matrix discards row/column names

Dear R-help,

When the result of a matrix subscription degenerates to a scalar the names
implied by the dimnames are discarded.
> x <- matrix(0, 1, 1, dimnames=list('a', 'x'))
## below I expected result to have names='x', it's
not
> x[1,]
[1] 0

## below I expected result to have names='a', it's
not
> x[,1]
[1] 0

This is probably a side effect of 'drop' applied to a 1*1 matrix, is
there an elegant way around?

One possibility could be to allow the 'drop' arg in '[' to take
numerical values (in addition to bool), which would be interpreted as dimensions
to drop.

Thanks,
Vadim

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Try this:

x[1,, drop = FALSE]


On Tue, Jul 21, 2009 at 1:46 PM, Vadim Ogranovich <
vogranovich@jumptrading.com> wrote:
> Dear R-help,
>
> When the result of a matrix subscription degenerates to a scalar the names
> implied by the dimnames are discarded.
>
> > x <- matrix(0, 1, 1, dimnames=list('a', 'x'))
>
> ## below I expected result to have names='x', it's not
> > x[1,]
> [1] 0
>
> ## below I expected result to have names='a', it's not
> > x[,1]
> [1] 0
>
> This is probably a side effect of 'drop' applied to a 1*1 matrix,
is there
> an elegant way around?
>
> One possibility could be to allow the 'drop' arg in '[' to
take numerical
> values (in addition to bool), which would be interpreted as dimensions to
> drop.
>
> Thanks,
> Vadim
>
> Note: This email is for the confidential use of the named addressee(s) only
> and may contain proprietary, confidential or privileged information. If you
> are not the intended recipient, you are hereby notified that any review,
> dissemination or copying of this email is strictly prohibited, and to
please
> notify the sender immediately and destroy this email and any attachments.
>  Email transmission cannot be guaranteed to be secure or error-free.  Jump
> Trading, therefore, does not make any guarantees as to the completeness or
> accuracy of this email or any attachments.  This email is for informational
> purposes only and does not constitute a recommendation, offer, request or
> solicitation of any kind to buy, sell, subscribe, redeem or perform any
type
> of transaction of a financial product.
>
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-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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