On Dec 21, 2011, at 11:31 AM, jim holtman wrote:
Here is an example using 'data.table'"
x <- read.table(text = "param case1
+ 1 a
+ 2 b
+ 2 c
+ 2 d
+ 3 e
+ 4 f", header = TRUE, as.is = TRUE)
And the aggregate version:
> aggregate(x$case1, x["param"], FUN=paste, collapse=",")
param x
1 1 a
2 2 b,c,d
3 3 e
4 4 f
( Generally one uses the "[[" function for extraction, but using "["
returns a list which is what aggregate is designed to process as its
second argument, whereas you would get an error with either of these:
aggregate(x$case1, x$param, FUN=paste, collapse=",")
aggregate(x$case1, x[["param"]], FUN=paste, collapse=",")
)
require(data.table)
x <- data.table(x)
x[
+ , list( case1 = paste(case1, collapse = ','))
+ , by = param
+ ]
param case1
[1,] 1 a
[2,] 2 b,c,d
[3,] 3 e
[4,] 4 f
On Wed, Dec 21, 2011 at 11:26 AM, Mary Kindall
<mary.kind...@gmail.com> wrote:
Hi
I have a data frame with values in following format.
param case1
1 a
2 b
2 c
2 d
3 e
4 f
how to use aggregate so that it I only one row for each 'param'
value.
the output for the above input should be
param case1
1 a
2 b,c,d
3 e
4 f
Thanks
M
--
-------------
Mary Kindall
Yorktown Heights, NY
USA
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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.
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David Winsemius, MD
West Hartford, CT
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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