[19136] in s-news-athena
[S] summary: converting a list of dataframes into a single dataframe
daemon@ATHENA.MIT.EDU (John.Gavin@wdr.com)
Wed Sep 8 03:25:42 1999
From: John.Gavin@wdr.com
Date: Wed, 8 Sep 1999 08:19:03 +0100
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Hi,
Many thanks for the prompt replies.
Solutions, credits and original question follow below.
Regards,
John.
Solutions
---------
There were two solutions.
The first did exactly what I wanted
1) do.call("rbind",input)
2) output <- NULL
while(length(input) > 0)
{
output <- rbind(output, input[[1]])
input[[1]] <- NULL
}
Credits
-------
Bill Venables Bill.Venables@cmis.csiro.au
cberry@tajo.ucsd.edu
Tim Hesterberg timh@statsci.com
Hong Ooi hong.ooi@maths.anu.edu.au
Original question
-----------------
I have a long list of data frames.
Each data frame has identical columns
(same number of columns, in the same order
and of the same class).
How can I produce a new single data frame formed by
stacking each data frame in the list one on
top of the other.
I am aware of the 'data - merge' command but
the list is too long to do two data frames at a time.
In effect, I want to reverse the data split command.
Also each data frame may contain 'factor' and 'ordered' columns
so I want to preserve the original labels.
I am on SPlus 2000 on NT 4.
Example: given the list 'input' I want to produce
the data frame 'output'.
input <- list(
a = data.frame(
x = c(1.0,2,3),
y = factor(c(1,1,2), levels = 1:3, labels = c("f1", "f2", "f3") ),
z = ordered(c(2,2,1), levels = 1:3, labels = c("o1","o2","o3") )
) ,
b = data.frame(
x = c(4,5),
y = factor(c(3,3), levels = 1:3, labels = c("f1","f2","f3") ),
z = ordered(c(3,2), levels = 1:3, labels = c("o1", "o2","o3") )
)
)
> input
$a:
x y z
1 1 f1 o2
2 2 f1 o2
3 3 f2 o1
$b:
x y z
1 4 f3 o3
2 5 f3 o2
output <- data.frame(
x = c(1.0,2,3,4,5) ,
y = factor(c(1,1,2,3,3), levels = 1:3, labels = c("f1", "f2",
"f3") ) ,
z = ordered(c(2,2,1,3,2), levels = 1:3, labels =
c("o1","o2","o3") )
)
> output
x y z
1 1 f1 o2
2 2 f1 o2
3 3 f2 o1
4 4 f3 o3
5 5 f3 o2
john.gavin@ubs.com
John Gavin
Quantitative Risk Models and Statistics
Warburg Dillon Read
1 Finsbury Ave (4th floor)
London EC2M 2PP, UK
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