Message-ID: <CAAxdm-6nj90yb1P-oxs+m_eAwu2LvmDq17CxT=5R-AYeGNgizg@mail.gmail.com>
Date: 2012-11-09T20:58:40Z
From: jim holtman
Subject: as.data.frame(do.call(rbind, lapply)) produces something weird
In-Reply-To: <87mwyqd1ks.fsf@gnu.org>
This is a case where you start by breaking down you complex one-liner
into separate statements and examine what the results are at each
point. This is what I would have to do with the script you posted.
I think as Bill pointed out, one of your function calls is probably
creating a result that you were not expecting. Standard (good)
programming practice would have you creating a number of simple
statements; this allows ease of debugging.
On Fri, Nov 9, 2012 at 2:21 PM, Sam Steingold <sds at gnu.org> wrote:
> The following code:
> --8<---------------cut here---------------start------------->8---
>> myfun <- function (x) list(x=x,y=x*x)
>> z <- as.data.frame(do.call(rbind,lapply(1:3,function(x) c(a=paste("a",x,sep=""),as.list(unlist(list(b=myfun(x),c=myfun(x*x*x))))))))
>> z
> a b.x b.y c.x c.y
> 1 a1 1 1 1 1
> 2 a2 2 4 8 64
> 3 a3 3 9 27 729
> --8<---------------cut here---------------end--------------->8---
> the appearance of z is good, but str() and summary betray some weirdness:
> --8<---------------cut here---------------start------------->8---
>> str(z)
> 'data.frame': 3 obs. of 5 variables:
> $ a :List of 3
> ..$ : chr "a1"
> ..$ : chr "a2"
> ..$ : chr "a3"
> $ b.x:List of 3
> ..$ : int 1
> ..$ : int 2
> ..$ : int 3
> $ b.y:List of 3
> ..$ : int 1
> ..$ : int 4
> ..$ : int 9
> $ c.x:List of 3
> ..$ : int 1
> ..$ : int 8
> ..$ : int 27
> $ c.y:List of 3
> ..$ : int 1
> ..$ : int 64
> ..$ : int 729
> --8<---------------cut here---------------end--------------->8---
> how do I ensure that the columns of z are vectors, as in
> --8<---------------cut here---------------start------------->8---
>> z <- data.frame(a=c("a1","a2","a3"),b.x=c(1,2,3),b.y=c(1,4,9),c.x=c(1,8,27),c.y=c(1,64,729))
>> z
> a b.x b.y c.x c.y
> 1 a1 1 1 1 1
> 2 a2 2 4 8 64
> 3 a3 3 9 27 729
>> str(z)
> 'data.frame': 3 obs. of 5 variables:
> $ a : Factor w/ 3 levels "a1","a2","a3": 1 2 3
> $ b.x: num 1 2 3
> $ b.y: num 1 4 9
> $ c.x: num 1 8 27
> $ c.y: num 1 64 729
> --8<---------------cut here---------------end--------------->8---
> thanks!
>
> --
> Sam Steingold (http://sds.podval.org/) on Ubuntu 12.04 (precise) X 11.0.11103000
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> Programming is like sex: one mistake and you have to support it for a lifetime.
>
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--
Jim Holtman
Data Munger Guru
What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.