FAQ
Dear All,

Assume I have a data.frame that contains also factors and I would like to
get another data.frame containing the factors as numeric vectors, to apply
functions like sapply(..., median) on them.
I read the warning concerning as.numeric or unclass, but in my case this
makes sense, because the factor levels are properly ordered.
I can do it, if I write for each single column "unclass(...), but I would
like to use indexing, e.g. unclass(df[1:10]).
Is that possible?

Thanks,
Heinz T?chler

## Example:
f1 <- factor(c(rep('c1-low',2),rep('c2-med',5),rep('c3-high',3)))
f2 <- factor(c(rep('c1-low',5),rep('c2-low',3),rep('c3-low',2)))
df.f12 <- data.frame(f1,f2) # data.frame containing factors

## this does work
df.f12.num <- data.frame(unclass(df.f12[[1]]),unclass(df.f12[[2]]))
df.f12.num
## this does not work
df.f12.num <- data.frame(unclass(df.f12[[1:2]]))
df.f12.num
## this does not work
df.f12.num <- data.frame(unclass(df.f12[1:2]))
df.f12.num

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•  at Apr 2, 2005 at 12:15 pm ⇧
Try this:

data.matrix(df.f12)
On Apr 2, 2005 6:01 AM, Heinz Tuechler wrote:
Dear All,

Assume I have a data.frame that contains also factors and I would like to
get another data.frame containing the factors as numeric vectors, to apply
functions like sapply(..., median) on them.
I read the warning concerning as.numeric or unclass, but in my case this
makes sense, because the factor levels are properly ordered.
I can do it, if I write for each single column "unclass(...), but I would
like to use indexing, e.g. unclass(df[1:10]).
Is that possible?

Thanks,
Heinz T?chler

## Example:
f1 <- factor(c(rep('c1-low',2),rep('c2-med',5),rep('c3-high',3)))
f2 <- factor(c(rep('c1-low',5),rep('c2-low',3),rep('c3-low',2)))
df.f12 <- data.frame(f1,f2) # data.frame containing factors

## this does work
df.f12.num <- data.frame(unclass(df.f12[[1]]),unclass(df.f12[[2]]))
df.f12.num
## this does not work
df.f12.num <- data.frame(unclass(df.f12[[1:2]]))
df.f12.num
## this does not work
df.f12.num <- data.frame(unclass(df.f12[1:2]))
df.f12.num

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
•  at Apr 2, 2005 at 12:31 pm ⇧

At 07:15 02.04.2005 -0500, Gabor Grothendieck wrote:
Try this:

data.matrix(df.f12)
Perfect! This is exactly what I needed.

Many thanks,
Heinz T?chler
On Apr 2, 2005 6:01 AM, Heinz Tuechler wrote:
Dear All,

Assume I have a data.frame that contains also factors and I would like to
get another data.frame containing the factors as numeric vectors, to apply
functions like sapply(..., median) on them.
I read the warning concerning as.numeric or unclass, but in my case this
makes sense, because the factor levels are properly ordered.
I can do it, if I write for each single column "unclass(...), but I would
like to use indexing, e.g. unclass(df[1:10]).
Is that possible?

Thanks,
Heinz T?chler

## Example:
f1 <- factor(c(rep('c1-low',2),rep('c2-med',5),rep('c3-high',3)))
f2 <- factor(c(rep('c1-low',5),rep('c2-low',3),rep('c3-low',2)))
df.f12 <- data.frame(f1,f2) # data.frame containing factors

## this does work
df.f12.num <- data.frame(unclass(df.f12[[1]]),unclass(df.f12[[2]]))
df.f12.num
## this does not work
df.f12.num <- data.frame(unclass(df.f12[[1:2]]))
df.f12.num
## this does not work
df.f12.num <- data.frame(unclass(df.f12[1:2]))
df.f12.num

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
•  at Apr 2, 2005 at 1:26 pm ⇧

On Sat, 2 Apr 2005, Heinz Tuechler wrote:

Dear All,

Assume I have a data.frame that contains also factors and I would like to
get another data.frame containing the factors as numeric vectors, to apply
functions like sapply(..., median) on them.
I read the warning concerning as.numeric or unclass, but in my case this
makes sense, because the factor levels are properly ordered.
I can do it, if I write for each single column "unclass(...), but I would
like to use indexing, e.g. unclass(df[1:10]).
Is that possible?
Yes: unclass is applied to a column and not the data frame.

newdf <- df
newdf[1:10] <- lapply(newdf[1:10], unclass)

BTW, please read the posting guide, and do not say `does not work' when it
patently does work as documented.
Thanks,
Heinz T?chler

## Example:
f1 <- factor(c(rep('c1-low',2),rep('c2-med',5),rep('c3-high',3)))
f2 <- factor(c(rep('c1-low',5),rep('c2-low',3),rep('c3-low',2)))
df.f12 <- data.frame(f1,f2) # data.frame containing factors

## this does work
df.f12.num <- data.frame(unclass(df.f12[[1]]),unclass(df.f12[[2]]))
df.f12.num
## this does not work
df.f12.num <- data.frame(unclass(df.f12[[1:2]]))
Yes, it does work. What do you think [[1:2]] does? Please RTFM.
## this does not work
df.f12.num <- data.frame(unclass(df.f12[1:2]))
df.f12.num
That also works: unclassing a data frame gives a list.

--
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
•  at Apr 2, 2005 at 12:43 pm ⇧

At 14:26 02.04.2005 +0100, Prof Brian Ripley wrote:
On Sat, 2 Apr 2005, Heinz Tuechler wrote:

Dear All,

Assume I have a data.frame that contains also factors and I would like to
get another data.frame containing the factors as numeric vectors, to apply
functions like sapply(..., median) on them.
I read the warning concerning as.numeric or unclass, but in my case this
makes sense, because the factor levels are properly ordered.
I can do it, if I write for each single column "unclass(...), but I would
like to use indexing, e.g. unclass(df[1:10]).
Is that possible?
Yes: unclass is applied to a column and not the data frame.

newdf <- df
newdf[1:10] <- lapply(newdf[1:10], unclass)

BTW, please read the posting guide, and do not say `does not work' when it
patently does work as documented.
Thank you for your answer. I am sorry for the unprecise formulation `does
not work'. I intended `does not solve my problem'.
In the meantime Gabor Grothendieck responded with:
'Try this: data.matrix(df.f12)'
which is exactly, what I was searching for.

Many thanks,
Heinz T?chler

Thanks,
Heinz T?chler

## Example:
f1 <- factor(c(rep('c1-low',2),rep('c2-med',5),rep('c3-high',3)))
f2 <- factor(c(rep('c1-low',5),rep('c2-low',3),rep('c3-low',2)))
df.f12 <- data.frame(f1,f2) # data.frame containing factors

## this does work
df.f12.num <- data.frame(unclass(df.f12[[1]]),unclass(df.f12[[2]]))
df.f12.num
## this does not work
df.f12.num <- data.frame(unclass(df.f12[[1:2]]))
Yes, it does work. What do you think [[1:2]] does? Please RTFM.
## this does not work
df.f12.num <- data.frame(unclass(df.f12[1:2]))
df.f12.num
That also works: unclassing a data frame gives a list.

--
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595

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