On Apr 6, 2009, at 6:31 PM, Jun Shen wrote:
This is a good example to compare different approaches. My
understanding is
aggregate() can apply one function to multiple columns
summarize() can apply multiple functions to one column
I am not sure if ddply() can actually apply multiple functions to
multiple
columns? This is what I would like to do. The syntax in the help is a
little confusing to me. Appreciate more comments. Thanks
This looks reasonably straight-forward:
lapply(c(mean,sd, length), function(func)
{aggregate(state.x77, list(Region =
state.region), func)} )
--
David Winsemius
Jun
On Mon, Apr 6, 2009 at 9:51 AM, Stavros Macrakis <macra...@alum.mit.edu
>wrote:
Actually, ddply does this perfectly ... I had made a mistake in using
'each'. The correct code is:
ddply(dd,~b+c,function(x)each(count=length,sum=sum,avg=mean)(x$a))
b c count sum avg
1 1 1 2 10 5.000000
2 2 1 1 3 3.000000
3 3 1 1 10 10.000000
4 1 2 2 10 5.000000
5 1 3 1 5 5.000000
6 3 3 3 17 5.666667
Hope this helps,
-s
On Mon, Apr 6, 2009 at 10:34 AM, Stavros Macrakis <macra...@alum.mit.edu
wrote:
There are various ways to do this in R.
# sample data
dd <-
data.frame(a=1:10,b=sample(3,10,replace=T),c=sample(3,10,replace=T))
Using the standard built-in functions, you can use:
*** aggregate ***
aggregate(dd,list(b=dd$b,c=dd$c),sum)
b c a b c
1 1 1 10 2 2
2 2 1 3 2 1
....
*** tapply ***
tapply(dd$a,interaction(dd$b,dd$c),sum)
1.1 2.1 3.1 1.2 2.2 3.2 1.3
2.3
5.000000 3.000000 10.000000 5.000000 NA NA 5.000000
...
But the nicest way is probably to use the plyr package:
library(plyr)
ddply(dd,~b+c,sum)
b c V1
1 1 1 14
2 2 1 6
....
********
Unfortunately, none of these approaches allows you do return more
than
one
result from the function, so you'll need to write
ddply(dd,~b+c,length) # count
ddply(dd,~b+c,sum)
ddply(dd,~b+c,mean) # arithmetic average
There is an 'each' function in plyr, but it doesn't seem to be
compatible
with ddply.
-s
On Mon, Apr 6, 2009 at 5:37 AM, calpeda <mauro.bias...@calpeda.it>
wrote:
Hi,
I ve been searching a lot in internet..but I can t find a solution
Attached, you find a file.
I need for each (Materiale, tpdv, UM) to find sum,avg and count
My idea was to aggregate for the 3 parameters ..but I don t know
how to
get
the numeric value (SUM,COUNT,AVG) I need.
Can you help me?
thank you
http://www.nabble.com/file/p22905322/ordini2008_ex.txtordini2008_ex.txt
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--
Jun Shen PhD
PK/PD Scientist
BioPharma Services
Millipore Corporation
15 Research Park Dr.
St Charles, MO 63304
Direct: 636-720-1589
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______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
