Excellent!
I felt it was fairly trivial but i can be quite dense on Friday
mornings.
I really like the generalisation.
Many thanks,
baptiste
On 3 Apr 2009, at 12:11, Wacek Kusnierczyk wrote:
baptiste auguie wrote:
Dear list,
I often need to convert several variables from numeric or integer
into
factors (before plotting, for instance), as in the following example,
d <- data.frame(
x = seq(1, 10),
y = seq(1, 10),
z = rnorm(10),
a = letters[1:10])
d2 <-
within(d, {
x = factor(x)
y = factor(y)
})
str(d)
str(d2)
I'd like to write a function factorise() which takes a data.frame and
a vector of variable names, and returns the original data.frame with
the desired variables converted to factor,
would this not be good enough:
# dummy data
data = data.frame(x=1:10, y=1:10)
# a factorizer
factorize = function(data, columns=names(data)) {
data[columns] = lapply(data[columns], as.factor)
data }
sapply(factorize(data, 'x'), is)
# $x "factor" ...
# $y "integer" ...
lapply(factorize(data), is)
# $x "factor" ...
# $y "factor" ...
factorise <- function(d, f)
***ply(d, f, factor) # some apply function
also, perhaps a defactorise() function doing the reverse operation
with as.numeric.
then, perhaps,
# an izer
ize = function(data, columns=names(data), izer=as.factor) {
data[columns] = lapply(data[columns], izer)
data }
ize(data, 'x', as.logical)
or even
ize = function(izer)
function(data, columns=names(data)) {
data[columns] = lapply(data[columns], izer)
data }
logicalize = ize(as.logical)
characterize = ize(as.character)
lapply(logicalize(data), is)
# $x "logical" ...
# $y "logical" ...
lapply(characterize(data, 'x'), is)
# $x "character" ...
# $y "integer" ...
etc.
vQ
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_____________________________
Baptiste Auguié
School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK
Phone: +44 1392 264187
http://newton.ex.ac.uk/research/emag
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
