Also,
you can check:
http://stackoverflow.com/questions/7235421/how-to-ddply-without-sorting
keeping.order <- function(data, fn, ...) {
col <- ".sortColumn"
data[,col] <- 1:nrow(data)
out <- fn(data, ...)
if (!col %in% colnames(out)) stop("Ordering column not preserved by
function")
out <- out[order(out[,col]),]
out[,col] <- NULL
out
}
x <- iris[ order(iris$Species, decreasing=T), ]
xa<-
ddply(x,.(Species),mutate,mean.adj=Sepal.Length-mean(Sepal.Length))[-c(2:4)]
xa1<-
keeping.order(x,ddply,.(Species),mutate,mean.adj=Sepal.Length-mean(Sepal.Length))[-c(2:4)]
head(xa1)
# Sepal.Length Species mean.adj
#101 6.3 virginica -0.288
#102 5.8 virginica -0.788
#103 7.1 virginica 0.512
#104 6.3 virginica -0.288
#105 6.5 virginica -0.088
#106 7.6 virginica 1.012
A.K.
----- Original Message -----
From: arun <smartpink...@yahoo.com>
To: Liviu Andronic <landronim...@gmail.com>
Cc: R help <r-help@r-project.org>
Sent: Monday, May 27, 2013 10:06 AM
Subject: Re: [R] configure ddply() to avoid reordering of '.variables'
May be this helps
levels(x$Species)
#[1] "setosa" "versicolor" "virginica"
x$Species<- factor(x$Species,levels=unique(x$Species))
xa <- ddply(x, .(Species), function(x)
{data.frame(Sepal.Length=x$Sepal.Length, mean.adj=(x$Sepal.Length -
mean(x$Sepal.Length)))})
head(xa)
# Species Sepal.Length mean.adj
#1 virginica 6.3 -0.288
#2 virginica 5.8 -0.788
#3 virginica 7.1 0.512
#4 virginica 6.3 -0.288
#5 virginica 6.5 -0.088
#6 virginica 7.6 1.012
A.K.
----- Original Message -----
From: Liviu Andronic <landronim...@gmail.com>
To: "r-help@r-project.org Help" <r-help@r-project.org>
Cc:
Sent: Monday, May 27, 2013 4:47 AM
Subject: [R] configure ddply() to avoid reordering of '.variables'
Hello,
I'm using ddply() in plyr and I notice that it has the habit of
re-ordering the levels of the '.variables' by which the splitting is
done. I'm concerned about correctly retrieving the original ordering.
Consider:
require(plyr)
x <- iris[ order(iris$Species, decreasing=T), ]
head(x)
# Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#101 6.3 3.3 6.0 2.5 virginica
#102 5.8 2.7 5.1 1.9 virginica
#103 7.1 3.0 5.9 2.1 virginica
#104 6.3 2.9 5.6 1.8 virginica
#105 6.5 3.0 5.8 2.2 virginica
#106 7.6 3.0 6.6 2.1 virginica
xa <- ddply(x, .(Species), function(x)
{data.frame(Sepal.Length=x$Sepal.Length, mean.adj=(x$Sepal.Length -
mean(x$Sepal.Length)))})
#
|==============================================================================================|
100%
##notice how the ordering of Species is different
##from that in the input data frame
head(xa)
# Species Sepal.Length mean.adj
#1 setosa 5.1 0.094
#2 setosa 4.9 -0.106
#3 setosa 4.7 -0.306
#4 setosa 4.6 -0.406
#5 setosa 5.0 -0.006
#6 setosa 5.4 0.394
all.equal(xa$Species, x$Species)
#[1] "100 string mismatches"
all.equal(xa[ order(xa$Species, decreasing=T), ]$Species, x$Species)
#[1] TRUE
all.equal(xa$Sepal.Length, x$Sepal.Length)
#[1] "Mean relative difference: 0.2785"
all.equal(xa[ order(xa$Species, decreasing=T), ]$Sepal.Length, x$Sepal.Length)
#[1] TRUE
In my real data, should I be concerned that simply reordering by the
'.variables' variable wouldn't necessarily restore the original
ordering as in the input data frame? Is it possible to instruct
ddply() to avoid re-ordering the supplied '.variables' variable?
Regards,
Liviu
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