R help - May 2006 - How to call a value labels attribute?

Dear All,

after searching on CRAN I got the impression that there is no standard way
in R to label values of a numerical variable.
Since this would be useful for me I intend to create such an attribute, at
the moment for my personal use.
Still I would like to choose a name which does not conflict with names of
commonly used attributes.

Would value.labels or vallabs create conflicts?

The attribute should be structured as data.frame with two columns, levels
(numeric) and labels (character). These could then also be used to
transform from numeric to factor. If the attribute is copied to the factor
variable it could also serve to retransform the factor to the original
numerical variable.

Comments? Ideas?

Thanks

Heinz T?chler

>>>>> "Heinz" == Heinz Tuechler <tuechler at
gmx.at>
>>>>>     on Tue, 23 May 2006 01:17:21 +0100 writes:
    Heinz> Dear All, after searching on CRAN I got the
    Heinz> impression that there is no standard way in R to
    Heinz> label values of a numerical variable.  

Hmm, there's  names(.)  and  "names(.) <- .."
Why are those not sufficient?

x <- 1:3
names(x) <- c("apple", "banana", NA)


    Heinz> Since this
    Heinz> would be useful for me I intend to create such an
    Heinz> attribute, at the moment for my personal use.  Still
    Heinz> I would like to choose a name which does not conflict
    Heinz> with names of commonly used attributes.

    Heinz> Would value.labels or vallabs create conflicts?

    Heinz> The attribute should be structured as data.frame with
    Heinz> two columns, levels (numeric) and labels
    Heinz> (character). These could then also be used to
    Heinz> transform from numeric to factor. If the attribute is
    Heinz> copied to the factor variable it could also serve to
    Heinz> retransform the factor to the original numerical
    Heinz> variable.

    Heinz> Comments? Ideas?

    Heinz> Thanks

    Heinz> Heinz T?chler

    Heinz> ______________________________________________
    Heinz> R-help at stat.math.ethz.ch mailing list
    Heinz> https://stat.ethz.ch/mailman/listinfo/r-help PLEASE
    Heinz> do read the posting guide!
    Heinz> http://www.R-project.org/posting-guide.html

At 14:12 03.06.2006 +0200, Martin Maechler wrote:
>>>>>> "Heinz" == Heinz Tuechler <tuechler at
gmx.at>
>>>>>>     on Tue, 23 May 2006 01:17:21 +0100 writes:
>
>    Heinz> Dear All, after searching on CRAN I got the
>    Heinz> impression that there is no standard way in R to
>    Heinz> label values of a numerical variable.  
>
>Hmm, there's  names(.)  and  "names(.) <- .."
>Why are those not sufficient?
>
>x <- 1:3
>names(x) <- c("apple", "banana", NA)
Martin,

I will considere this. For now I am using an attribute value.labels and a
corresponding class to preserve this and other attributes after inclusion
in a data.frame and indexing/subsetting, but using names should do as well.
My idea was more like defining a set of value labels for a variable and
apply it to all the variable, as e.g. in the following _pseudocode_:

### not run
### pseudocode
x <- c(1, 2, 3, 3, 2, 3, 1)
value.labels(x) <- c(apple=1, banana=2, NA=3)
x
### desired result
apple banana  NA  NA banana NA apple
    1      2   3   3      2  3     1

value.labels(x) <- c(Apfel=1, Banane=2, Birne=3) # redefine labels
x
### desired result
Apfel Banane Birne Birne Banane Birne Apfel
    1      2     3     3      2     3     1

value.labels(x) # inspect labels
### desired result
Apfel Banane Birne
    1      2     3

These value.labels should persist even after inclusion in a data.frame and
after indexing/subsetting.
I did not yet try your idea concerning these aspects, but I will do it. My
final goal is to do all the data handling on numerically coded variables
and to transform to factors "on the fly" when needed for statistical
procedures. Given the presence of value.labels a factor function could use
them for the conversion.

I described my motivation for all this in a previous post, titled:
How to represent a metric categorical variable?
There was no response at all and I wonder, if this is such a rare problem.

Thanks,
Heinz
>
>
>    Heinz> Since this
>    Heinz> would be useful for me I intend to create such an
>    Heinz> attribute, at the moment for my personal use.  Still
>    Heinz> I would like to choose a name which does not conflict
>    Heinz> with names of commonly used attributes.
>
>    Heinz> Would value.labels or vallabs create conflicts?
>
>    Heinz> The attribute should be structured as data.frame with
>    Heinz> two columns, levels (numeric) and labels
>    Heinz> (character). These could then also be used to
>    Heinz> transform from numeric to factor. If the attribute is
>    Heinz> copied to the factor variable it could also serve to
>    Heinz> retransform the factor to the original numerical
>    Heinz> variable.
>
>    Heinz> Comments? Ideas?
>
>    Heinz> Thanks
>
>    Heinz> Heinz T?chler
>
>    Heinz> ______________________________________________
>    Heinz> R-help at stat.math.ethz.ch mailing list
>    Heinz> https://stat.ethz.ch/mailman/listinfo/r-help PLEASE
>    Heinz> do read the posting guide!
>    Heinz> http://www.R-project.org/posting-guide.html
>
>

Aha!  Thank you for the more detailed example.

My solution for that situation is an attribute "position" and function
as.position().  I use this in my book

                Statistical Analysis and Data Display
                Richard M. Heiberger and Burt Holland

The online files for the book are available at
                http://springeronline.com/0-387-40270-5



For this example, you need the function as.position() included in this
email.


### example ########
x <- ordered(c(1,2,3,2,4,3,1,2,4,3,2,1,3),
             labels=c("small", "medium", "large",
"very.large"))
x
attr(x, "position") <- c(1,2,4,8)
x
as.position(x)

y <- rnorm(length(x))
y

xyplot(y ~ x)
source("~/h2/library/code/as.position.s")
xyplot(y ~ as.position(x))
xyplot(y ~ as.position(x),
       scale=list(x=list(at=attr(x,"position"), labels=levels(x))))
xyplot(y ~ as.position(x),
       scale=list(x=list(at=attr(x,"position"), labels=levels(x))),
       xlab="x")
### end example ########



### as.position.s #########
as.position <- function(x) {
  if (is.numeric(x))
    x
  else {
    if (!is.factor(x)) stop("x must be either numeric or factor.")

    if (!is.null(attr(x, "position")))
      x <- attr(x, "position")[x]
    else {
      lev.x <- levels(x)
      if (inherits(x, "ordered")) {
        on.exit(options(old.warn))
        old.warn <- options(warn=-1)
        if (!any(is.na(as.numeric(lev.x))))
          x <- as.numeric(lev.x)[x]
        else
          x <- as.numeric(ordered(lev.x, lev.x))[x]
      }
      else
        x <- as.numeric(x)
    }
  }
  x
}


## tmp <-
ordered(c("c","b","f","f","c","b"),
c("c","b","f"))
## as.numeric(tmp)
## as.position(tmp)
## 
## tmp <-
factor(c("c","b","f","f","c","b"))
## as.numeric(tmp)
## as.position(tmp)
## 
## tmp <- factor(c(1,3,5,3,5,1))
## as.numeric(tmp)
## as.position(tmp)
## 
## tmp <- ordered(c(1,3,5,3,5,1))
## as.numeric(tmp)
## as.position(tmp)
## 
## tmp <- c(1,3,5,3,5,1)
## as.numeric(tmp)
## as.position(tmp)

### end as.position.s #########

Thank you, Richard. As soon as I find time I will carefully look at your
solution and your book.

Heinz

At 10:01 05.06.2006 -0400, Richard M. Heiberger wrote:
>Aha!  Thank you for the more detailed example.
>
>My solution for that situation is an attribute "position" and
function
>as.position().  I use this in my book
>
>                Statistical Analysis and Data Display
>                Richard M. Heiberger and Burt Holland
>
>The online files for the book are available at
>                http://springeronline.com/0-387-40270-5
>
>
>
>For this example, you need the function as.position() included in this
>email.
>
>
>### example ########
>x <- ordered(c(1,2,3,2,4,3,1,2,4,3,2,1,3),
>             labels=c("small", "medium",
"large", "very.large"))
>x
>attr(x, "position") <- c(1,2,4,8)
>x
>as.position(x)
>
>y <- rnorm(length(x))
>y
>
>xyplot(y ~ x)
>source("~/h2/library/code/as.position.s")
>xyplot(y ~ as.position(x))
>xyplot(y ~ as.position(x),
>       scale=list(x=list(at=attr(x,"position"),
labels=levels(x))))
>xyplot(y ~ as.position(x),
>       scale=list(x=list(at=attr(x,"position"),
labels=levels(x))),
>       xlab="x")
>### end example ########
>
>
>
>### as.position.s #########
>as.position <- function(x) {
>  if (is.numeric(x))
>    x
>  else {
>    if (!is.factor(x)) stop("x must be either numeric or factor.")
>
>    if (!is.null(attr(x, "position")))
>      x <- attr(x, "position")[x]
>    else {
>      lev.x <- levels(x)
>      if (inherits(x, "ordered")) {
>        on.exit(options(old.warn))
>        old.warn <- options(warn=-1)
>        if (!any(is.na(as.numeric(lev.x))))
>          x <- as.numeric(lev.x)[x]
>        else
>          x <- as.numeric(ordered(lev.x, lev.x))[x]
>      }
>      else
>        x <- as.numeric(x)
>    }
>  }
>  x
>}
>
>
>## tmp <-
ordered(c("c","b","f","f","c","b"),
c("c","b","f"))
>## as.numeric(tmp)
>## as.position(tmp)
>## 
>## tmp <-
factor(c("c","b","f","f","c","b"))
>## as.numeric(tmp)
>## as.position(tmp)
>## 
>## tmp <- factor(c(1,3,5,3,5,1))
>## as.numeric(tmp)
>## as.position(tmp)
>## 
>## tmp <- ordered(c(1,3,5,3,5,1))
>## as.numeric(tmp)
>## as.position(tmp)
>## 
>## tmp <- c(1,3,5,3,5,1)
>## as.numeric(tmp)
>## as.position(tmp)
>
>### end as.position.s #########
>
>