On Mar 3, 2010, at 12:15 PM, William Dunlap wrote:
If R made
matrix$columnName
mean the same as
matrix[, "columnName"]
(a vector) so matrices looked more like data.frames,
would we also want the following to work
as they do with data.frames?
with(matrix, log(columnName)) # log of that column as a vector
matrix["columnName"] # 1-column matrix
matrix[["columnName"]] # vector equivalent of that 1-column matrix
lm(responseColumn~predictorColumn, data=matrix)
eval(quote(columnName), envir=matrix)
The last 2 bump into the rule allowing envir to be
a frame number (since a 1x1 matrix is currently taken
as the frame number now).
Perhaps the print methods for data.frame and matrix
should announce the class of the object being printed.
Yes! An enthusiastic vote for highlighting this fundamental
distinction. There is already quite enough conflation of these two
very dissimilar object classes.
--
David Winsemius
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
-----Original Message-----
From: r-help-boun...@r-project.org
[mailto:r-help-boun...@r-project.org] On Behalf Of Patrick Burns
Sent: Wednesday, March 03, 2010 2:44 AM
To: r-help@r-project.org
Subject: Re: [R] two questions for R beginners
I think Duncan's example of a list that is
a matrix is a compelling argument not to do
the change.
A matrix that is a list with both names and
dimnames *is* probably rare (but certainly
imaginable). A matrix that is a list is not
so rare, and the proposed double meaning of
'$' would certainly be confusing in that case.
Pat
On 02/03/2010 17:55, Duncan Murdoch wrote:
On 02/03/2010 11:53 AM, William Dunlap wrote:
-----Original Message-----
From: r-help-boun...@r-project.org >
[mailto:r-help-boun...@r-project.org] On Behalf Of John Sorkin
Sent: Tuesday, March 02, 2010 3:46 AM
To: Karl Ove Hufthammer; r-h...@stat.math.ethz.ch
Subject: Re: [R] two questions for R beginners
Please take what follows not as an ad hominem statement, but >
rather as an attempt to improve what is already an excellent >
program, that has been built as a result of many, many hours > of
dedicated work by many, many unpaid, unsung volunteers.
It troubles me a bit that when a confusing aspect of R is >
pointed out the response is not to try to improve the >
language so as
to avoid the confusion, but rather to state > that the confusion is
inherent in the language. I understand > that to make changes that
would avoid the confusing aspect of > the language that has been
discussed in this thread would > take time and effort by
an R wizard
(which I am not), time > and effort that would not be
compensated in
the traditional > sense. This does not mean that we should not
acknowledge the > confusion. If we what R to be the de facto lingua
franca of > statistical analysis doesn't it make sense to
strive for >
syntax that is as straight forward and consistent as possible?
Whenever one changes the language that way old code
will break.
I think in this case not much code would break. Mostly when
people have
a matrix M and ask for M$column they'll get an error; the
proposal is
that they'll get the requested column. (It is possible to
have a list
with names that is also a matrix with dimnames, but I think
that is a
pretty unusual construction.) But I haven't been convinced that the
proposal is a net improvement to the language.
Duncan Murdoch
The developers can, with a lot of effort,
fix their own code, and perhaps even user-written code
on CRAN, but code that thousands of users have written
will break. There is a lot of code out there that was
written by trial and error and by folks who no longer
work at an institution: the code works but no one knows
exactly why it works. Telling folks they need to change
that code because we have a cleaner but different syntax
now is not good. Why would one spend time writing a
package that might stop working when R is "upgraded"?
I think the solution is not to change current semantics
but to write functions that behave better and encourage
users to use them, gradually abandoning the old constructs.
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
Again, please understand that my comment is made with deepest >
respect for the many people who have unselfishly
contributed > to the
R project. Many thanks to each and every one of you.
John
Karl Ove Hufthammer <k...@huftis.org> 3/2/2010
4:00 AM >>>
On Mon, 01 Mar 2010 10:00:07 -0500 Duncan Murdoch >
<murd...@stats.uwo.ca> > wrote:
Suppose X is a dataframe or a matrix. What would you >
expect to
get from > > X[1]? What about as.vector(X), or as.numeric(X)?
All this of course depends on type of object one is
speaking > of.
There > are plenty of surprises available, and it's best
to use the >
most logical > way of extracting. E.g., to extract the top-left
element of a 2D > structure (data frame or matrix), use 'X[1,1]'.
Luckily, R provides some shortcuts. For example, you
can > write
'X[2,3]' > on a data frame, just as if it was a matrix, even though
the > underlying > structure is completely different. (This doesn't
work on a > normal list; > there you have to type the
whole 'X[[2]][3]'.)
The behaviour of the 'as.' functions may sometimes be
surprising,
at > least for me. For example, 'as.data.frame' on a named vector
gives a > single-column data frame, instead of a
single-row data frame.
(I'm not sure what's the recommended way of converting
a > named
vector to > row data frame, but 'as.data.frame(t(X))' works, even
though both 'X' > and 't(X)' looks like a row of numbers.)
The point is that a dataframe is a list, and a
matrix > isn't.
If users > > don't understand that, then they'll be confused
somewhere. Making > > matrices more list-like in one
respect will just
move the confusion > > elsewhere. The solution is to understand the
difference.
My main problem is not understanding the difference, which is >
easy, but > knowing which type of I have when I get the output a
function in a > package. If I know the object is a named
vector or a
matrix > with column > names, it's easy enough to type
'X[,"colname"]', and if it's a data > frame one may use
the shortcut
'X$colname'.
Usually, it *is* documented what the return value of a
function
is, but > just looking at the output is much faster, and *usually*
gives the > correct answer.
For example, 'mean' applied on a data frame gives a named >
vector, not a > data frame, which is somewhat surprising
(given that
the columns of a > data frame may be of different types, while the
elements of a > vector may > not). (And yes, I know that it's
*documented* that it returns a named > vector.) On the other hand,
perhaps it is surprising that > 'mean' works > on data
frames at all. :-)
-- > Karl Ove Hufthammer
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R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the
posting guide > http://www.R-project.org/posting-guide.html > and
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______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide >
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained,
reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
--
Patrick Burns
pbu...@pburns.seanet.com
http://www.burns-stat.com
(home of 'The R Inferno' and 'A Guide for the Unwilling S User')
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
