A table without names displays like a vector:
> unname(table(2:3))
[1] 1 1 1
and preserves the table class (as with unname in general):
> dput(unname(table(2:3)))
structure(c(1L, 1L), .Dim = 2L, class = "table")
Does that make sense? R is not consistent in its treatment of such unname'd
tables:
In plot, they are considered erroneous input:
> plot(unname(table(2:3)))
Error in xy.coords(x, y, xlabel, ylabel, log) :
'x' and 'y' lengths differ
but in melt, they act as though they have names 1:n:
> melt(unname(table(2:3)))
indicies value
1 1 1
2 2 1
(By the way, is the spelling error built into too much code to be
corrected?)
-s
PS What is the standard way of extracting just the underlying vector?
c(unname(...)) works -- is that what is recommended?
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On Jun 11, 2009, at 5:35 PM, Stavros Macrakis wrote:> A table without names displays like a vector: > >> unname(table(2:3)) > [1] 1 1 1 > > and preserves the table class (as with unname in general): > >> dput(unname(table(2:3))) > structure(c(1L, 1L), .Dim = 2L, class = "table") > > Does that make sense? R is not consistent in its treatment of such > unname'd > tables: > > In plot, they are considered erroneous input: > >> plot(unname(table(2:3))) > Error in xy.coords(x, y, xlabel, ylabel, log) : > 'x' and 'y' lengths differ > > but in melt, they act as though they have names 1:n: > >> melt(unname(table(2:3))) > indicies value > 1 1 1 > 2 2 1 > > (By the way, is the spelling error built into too much code to be > corrected?) > > -s > > PS What is the standard way of extracting just the underlying vector? > c(unname(...)) works -- is that what is recommended?I think of R (contingency) tables as just integer arrays with attitude ... er, attributes. > tt <- table(c(1,1,1,3,3,3,5,5)) > is.array(tt) [1] TRUE > is.matrix( with(warpbreaks, table(wool, tension)) ) [1] TRUE So what would you do with a matrix that had row or column names?> --David Winsemius, MD Heritage Laboratories West Hartford, CT
On 11/06/2009 5:35 PM, Stavros Macrakis wrote:> A table without names displays like a vector: > > > unname(table(2:3)) > [1] 1 1 1 > > and preserves the table class (as with unname in general): > > > dput(unname(table(2:3))) > structure(c(1L, 1L), .Dim = 2L, class = "table") > > Does that make sense? R is not consistent in its treatment of such unname'd > tables:One of the complaints about the S3 object system is that anything can claim to be of class "foo", even if it doesn't have the right structure so that foo methods work for it. I think that's all you're seeing here: you've got something that is mislabelled as being of class "table". The solution is "don't do that". > In plot, they are considered erroneous input:> > > plot(unname(table(2:3))) > Error in xy.coords(x, y, xlabel, ylabel, log) : > 'x' and 'y' lengths differ > > but in melt, they act as though they have names 1:n: > > > melt(unname(table(2:3))) > indicies value > 1 1 1 > 2 2 1 > > (By the way, is the spelling error built into too much code to be > corrected?) > > -s > > PS What is the standard way of extracting just the underlying vector? > c(unname(...)) works -- is that what is recommended?I would use as.numeric(), but I don't claim it's standard. Duncan Murdoch