From wdunlap at tibco.com  Thu Jul 20 18:56:18 2017
From: wdunlap at tibco.com (William Dunlap)
Date: Thu, 20 Jul 2017 09:56:18 -0700
Subject: [Rd] matrices with names
Message-ID: <CAF8bMcZbHHzAmyXfzGfyMFysBu5S=0eiXJ3RxycE7qhYw8Yb9Q@mail.gmail.com>

How should R deal with matrices that have a 'names' attribute?  S (and S+)
did not allow an object to have both dims and names but R does.  However,
some R functions copy the dims but not the names to the returned value and
some copy both.  I don't see a pattern to it.  Is there a general rule for
when the names on a matrix should be copied to the return value of a
function?

> x <- matrix(11,1,1)
> names(x)<-"One"
> dput(x)
structure(11, .Dim = c(1L, 1L), .Names = "One")
> dput(log2(x))
structure(3.4594316186373, .Dim = c(1L, 1L), .Names = "One")
> dput(pchisq(x,8))
structure(0.798300801297471, .Dim = c(1L, 1L), .Names = "One")
> dput(x+1)
structure(12, .Dim = c(1L, 1L))
> dput(x > 3)
structure(TRUE, .Dim = c(1L, 1L))
> dput(!x)
structure(FALSE, .Names = "One", .Dim = c(1L, 1L))
> dput(-x)
structure(-11, .Dim = c(1L, 1L), .Names = "One")
> dput(0-x)
structure(-11, .Dim = c(1L, 1L))

The binary operators don't copy, unary operators do copy, and many other
low-level functions do copy.

Bill Dunlap
TIBCO Software
wdunlap tibco.com

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[Rd] matrices with names
William Dunlap