R help - Sep 2007 - How to remove index from list after split?

In the following example, how can I drop the group index from the list after
I perform a split?
n     <- 3
nn   <- 10
g     <- factor(round(n * runif(n * nn)))
x     <- rnorm(n * nn) + sqrt(as.numeric(g))
df    <- data.frame(g,x)
df.s <- split(df,g)

Thanks!

Rick DeShon

	[[alternative HTML version deleted]]

Did not completely understand what is a 'group index', 
but to remove any element from a list or a matrix, or a vector or a data
frame you could use the negative index.

For example, 
> df.s[-c(1:3)]
$`3`
   g        x
1  3 3.916503
12 3 1.435718
24 3 2.252151
> df.s[-c(1:3)][[1]][-1]
          x
1  3.916503
12 1.435718
24 2.252151

You can also assign the results to a variable (the same or the other
one)
> df.s<-df.s[-c(1:3)][[1]][-1]
> df.s
          x
1  3.916503
12 1.435718
24 2.252151



Rick DeShon wrote:
> 
> In the following example, how can I drop the group index from the list
> after
> I perform a split?
> n     <- 3
> nn   <- 10
> g     <- factor(round(n * runif(n * nn)))
> x     <- rnorm(n * nn) + sqrt(as.numeric(g))
> df    <- data.frame(g,x)
> df.s <- split(df,g)
> 
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Not sure what you mean by "group index" but try: 

lapply(df.s,function(l){l$x})
or something like: 

do.call("rbind",df.s) 

to convert the result into a data.frame. 

Regards

Wayne



-----Original Message-----
From: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org]On Behalf Of Rick DeShon
Sent: 14 September 2007 11:50
To: r-help at stat.math.ethz.ch
Subject: [R] How to remove index from list after split?


In the following example, how can I drop the group index from the list after
I perform a split?
n     <- 3
nn   <- 10
g     <- factor(round(n * runif(n * nn)))
x     <- rnorm(n * nn) + sqrt(as.numeric(g))
df    <- data.frame(g,x)
df.s <- split(df,g)

Thanks!

Rick DeShon

	[[alternative HTML version deleted]]

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